You’ve heard of raised beds and garden beds, but what about nursery beds? Nursery beds are the perfect place for that “just couldn’t pass it up” seedling, the gift plant with no permanent location, sale priced plants that you haven’t had time to work into your regular garden or landscape, or it can be used as a quarantine station. These are all plants that may need a little extra care or attention, as they settle in. Maintaining a nursery bed takes up very little time or space, but it can save you a lot of money on plants.
What is a nursery bed? A nursery bed may simply be a plot of ground, tucked away in a corner of the yard. It may be a slightly raised area, walled in with cinderblocks or scrap lumber. Nursery beds do not have to be pretty. They simply need soil, water, and sunlight. If you want to get fancy, you can add corner posts to support protective netting or shade cloth. Again, looks are not important. Start seeds in a nursery bed Vegetable seeds can be started in a nursery bed, and grown there until they are big enough for transplanting. This is an excellent tool for succession planting. As you wait for the current crop to wind down, your next season’s crop is already on its way! Nursery beds are also a great place to start plants that can be used to fill empty spots as they occur. As a tomato plant gives up the ghost, simply cut it off at ground level and install a cheery chrysanthemum in its place! Viola! Transplant recovery in a nursery bed Most gardeners feel frustrated by thinning young seedlings. A nursery bed offers the perfect place to put the removed seedlings, allowing them a chance to recover from the ordeal and, possibly, grow to a large enough size to be moved elsewhere, or gifted to a friend or neighbor. Propagating with a nursery bed If you want to try you hand at vegetative propagation, nursery beds provide an easy starting point for cuttings and divisions, allowing them time to recover and to develop new roots before being moved to more permanent locations. Nursery beds also provide a good location to start parent plants that will ultimately be divided into many smaller plants (for a tiny fraction of the cost of buying all mature plants). Nursery beds for hardening off Delicate seedlings may need a transitionary period before they can handle being planted in the garden. With the addition of shade cloth or old glass windows, cold frame style, you can give these babies a taste of the great outdoors without exposing them to more than they can handle. How to make a nursery bed While you want your nursery bed to be convenient to the rest of the garden (and a hose bib), it can easily be tucked away behind a shed or some shrubs, as long as it gets at least 6 to 8 hours of sunlight each day, and is relatively level. Being sheltered is actually a bonus for a nursery bed, as it helps block strong winds. Use these steps to create your own nursery bed:
Nursery beds are different from raised beds in that they are designated as an unplanned, layover location, rather than a permanent home. Finally, if you have a nursery bed set up and know that you won’t be using it for a while, it makes a great place to age compost. The nutrients left behind will be exactly what all those baby plants need to thrive! Geocarpy is a rare form of plant reproduction that practiced by peanuts and a few other plants you may, or may not, recognize. While most plants wave their flowers at pollinators and then allow their fruit to swing freely, out in clear view, geocarpic plants are far more modest. Geocarpic plants tend to live in areas that are harsh. Seasonal fires, extreme drought, and repeated freezing and thawing (solifluction) can make plant life difficult. Because of all this uncertainty, these plants have decided that it is better to push their flowers underground to develop into fruit. The floral stem, or peduncle, does all the pushing. Types of geocarpy The term geocarpy refers to any plant that ripens its fruit underground. There are three forms of geocarpy: hysterocarpy, amphicarpiy, and protogeocarpy. If the ovaries are fertilized above ground and then pushed underground, it is called hysterocarpy. Peanuts are hysterocarpic. If only some of the fruits are pushed underground, it is called amphicarpic. Protogeocarpic reproduction is really wild. These plants produce their flowers underground. Think about it. How are pollinators supposed to transfer pollen to the flower if it is underground? Protogeocarpic plants have evolved a different type of flower. The stigmas, or pollen receptors, of protogeocarpic flowers push their way an inch or so above ground. Pollinators land on these threadlike, aerial stigmas, depositing pollen, which then travels down the stigma to the flower, underground. Here, the ovary is fertilized and fruit development occurs. I’m not sure why they have those names, but I like to think of plants waving their aboveground flowers ‘hysterically’ before heading underground, to remember which one is above ground. In addition to peanuts (Arachis hypogaea), South African bitter cress (Cardamine hirsuta) and the Genuflecting plant (Spigelia genuflexa) also use this unique method of reproduction.
Do you have any geocarpic plants in your garden? Square watermelons, portrait gourds, heart-shaped oranges, and Buddha pears are purposefully distorted fruits that can be a fun way to play with your plants. These distortions are kin to the method of tree training known as pleaching. When it occurs without human intervention, however, fruit distortions warrant a closer look. Affectionately known as ugly fruit, naturally occurring fruit distortions can be nothing more than cosmetic. Or, they may indicate the presence of pests, disease, nutrient deficiencies, or chemical misuse. It can also be from stress. Fruit distortions caused by stress Stressed plants (and people) do not perform as well as they might otherwise. If you were a plant, those stresses might be drought, insect damage, extreme temperatures, herbivore feeding, mechanical injury, excessive salt, insufficient nitrogen, severe weed competition, or water stress. If you were a stressed-out member of the cabbage family, you might surround yourself with a protective layer of bronzed leaves. Or you might shrink your head in a response called buttoning. Stress-induced distortions also include stunting, misshapen flowers, and reduced leaf size. Mechanical injury or blockage of cucumbers and other cucurbits can cause crooking. Low temperatures during pollination can cause uneven fruit development in strawberries. But what if it isn’t stress that is causing fruit distortion? Fruit distortions caused by nutrient deficiency Plant nutrients are critical to the proper development of fruit. Distorted fruits often occur in boron-deficient soil. Of course, without a soil test from a reputable lab, you won’t know what’s in your soil. Unfortunately, those cute, over-the-counter soil tests are not [yet] accurate enough to be helpful. Insects that cause fruit distortion Citrus bud mite feeding can cause some dramatic distortions, especially in citrus. While there isn’t anything you can do to get rid of citrus bud mites, their feeding can create points of entry for other pests and diseases, so you will want to monitor infested trees. Fungal disease and fruit distortion
Fungal diseases, such as apple scab, can also cause fruit distortion. Unfortunately, in this case, you won’t want to eat the fruit, as it will be mushy and rotten. One easy way to break the fungal disease triangle is to remove fallen leaves under infected trees and toss them in the trash. Chemicals and distorted fruit Since many herbicides are plant hormones (auxins) that force plants to grow so fast that they die, chemical misuse or overspray from a neighbor’s yard can cause fruit distortion. In this case, if in doubt, don’t eat it. If the suspected chemical is systemic, you won’t be able to wash it off. Unless fruit distortions are from chemicals or fungal disease, taste and texture are rarely affected. These fruits are simply funny looking. We can enjoy them for their uniqueness. Heliotropism refers to a plant’s ability to track the sun’s movement. For many centuries, it was believed that a plant’s tendency to follow the sun as it crossed the sky was a passive action caused by water loss on the side of the plant exposed to sunlight. Now, we know that there is far more to it than that. Growing toward sunlight Instead of passively shrinking to one side as the sun’s harsh rays boil away a plant’s bodily fluids, we now know that plants actively grow toward (or away from) sunlight. [When a plant grows away from sunlight, it is called skototropism.] Experiments conducted in the 1800’s demonstrated that plants will respond to any type of light: street lights, grow lights, or sunlight. When plants are attracted to this light, it is called phototropism. Phototropism is a function of the hypocotyl, or individual cells found in the same region. Hypocotyls are the embryonic stem found below the seed leaves (cotyledons) and directly above the root. You can easily see examples of phototropism when seedlings first emerge and they don’t get enough sunlight - they become leggy and lean toward whatever light they can. This is phototropism. In heliotropism, not any old light source will do. It is only radiation from the sun that causes the reaction. And the mechanical causes of these two types of movements are very different. Mechanics of plant movements When plants move in response to the position of an external stimulus, it is called a tropic [TRO-pic] movement. If a plant’s movement is independent of the stimuli’s position, it is called a nastic movement. In phototropism, plant hormones (auxins), found in the meristem tissue of leaf and stem tips, photoreceptors, and multiple signaling pathways are used to direct a plant to grow more rapidly toward sunlight. In heliotropism, a structure called the pulvinus is used to direct movement. The power of pulvinus The pulvinus is an amazing, fluid-controlled joint found at the base of a plant leaf stem (petiole) or just below a flower. The pulvinus causes movement by altering fluid pressure in the surrounding plant tissue. These changes in fluid pressure start when sucrose is moved from the phloem into the apoplast. The apoplast is the conjoined spaces between plant cells. As sugar is pumped into the apoplast, potassium ions are pushed out, followed by water molecules. This changes the pressure within the affected cells, causing movement. This is called turgor-mediated heliotropism. But not all heliotropic flowers have a pulvinus. Those that do not are still able to move by permanently expanding individual cells. This is called growth-mediated heliotropism. Pulvini are also used in response to nyctinastic and thigmonastic movements.
Heliotropic flowers Heliotropic flowers face the sun from dawn to dusk. Slowly tracking the sun’s path across the sky, these flowers are believed to use heliotropism as a way to improve pollination, fertilization, and seed development. Heliotropic flowers often have five times as many beneficial insects present, due to the added warmth. [Many tropical flowers exhibit a modified form of heliotropism in which flowers maintain an indirect tracking of the the sun. This is believed to reduce the chance of potential overheating.] Beans, alfalfa, sunflowers, and many other species turn their blooms to follow the sun’s path across the sky each day. But sunflowers only use heliotropism in their early development, in the bud stage. Once a sunflower head emerges, it may track the sun for a short time, as an expression of phototropism, until the flower head reaches full size. The majority of sunflowers found in the northern hemisphere nearly always end up facing east. Leaf heliotropism Like floral heliotropism, leaf heliotropism is the method by which plants focus their leaves perpendicularly to the sun’s morning rays (diaheliotropism), or parallel to midday sun (paraheliotropism). Diaheliotropism allows leaves to capture the maximum amount of energy from the sun, while paraheliotropism protects plants from overheating and dehydrating. How do your plants move during the day? Most fruits hang in their own singularity: apples, oranges, and apricots are common examples. Other fruits, such as grapes, form clusters. Still other fruits are formed when a group of flowers merge to create a fruit. Soroses are that type of fruit. What is fruit? Fruit is the fertilized ovary of a flowering plant (angiosperm). After pollination and fertilization occur, two new structures are produced: seeds (fertilized ovules) and pericarp (thickened ovary walls). In the case of apples and oranges, one flower produces one fruit. Sometimes, multiple flowers can fuse together to create a fruit. There are three different ways that this can happen:
In nearly every piece of literature you see, pineapples are listed as a common example of sorosis, but this is incorrect. I don’t know why they do this. How a sorosis fruit develops If you look at a mulberry flower cluster, you will see several flower buds held tightly together. Each of these individual flowers open up, awaiting pollination. If you look closely, you can see tiny fruits at the base of each flower. Each of these fertilized fruits will develop around the stem that they emerged from in the first place. This is unlike pineapples, which include the receptacles and flower parts in their fruit development. Berries vs. soroses While mulberries may appear to have the same structure as blackberries and raspberries, botanically, they are quite different. Raspberries and other members of Rubus are made up of several drupes (a type of fruit) that are clustered around and attached to a dry thalamus. All of the drupes in a single fruit are made from a single flower. In mulberries, and other soroses, each rounded bit is its own fruit, formed from its own flower. It won’t make any difference, as you enjoy a fig, some pineapple, or a mulberry, but now you can impress your friends with this fascinating word!
Some garden words are fun to say. Schizocarp [ˈskitsōˌkärp] certainly qualifies. A schizocarp is a type of dry fruit that splits into single-seeded parts, called mericarps, when ripe. Each mericarp is made from its own carpel. [A carpel is the female reproductive parts of a flower, including an ovary, stigma, and usually a style.] Mericarps can be dehiscent, which means they split open when ripe, or indehiscent, which means they stay closed. Indehiscent schizocarps The seeds of carrots, celery, coriander, anise, dill, parsnip, and other umbellifers are all indehiscent schizocarps. Hibiscus (Malvaceae), mallows and cheeseweeds (Malva), false mallows (Malvastrum), and wireweed (Sida acuta) fall in the same category. Dehiscent schizocarps Members of the Geranium genus produce dehiscent schizocarps. [These are not the garden variety geraniums, which are another genus altogether (Pelargonium). I know, I know, it gets confusing.] True Geranium species include the cranesbill, horns’ bill and filaree plants that produce needle-shaped schizocarps that twist and gyrate into the soil (and were fun to play with, when we were children). Maple trees produce winged schizocarps, called samaras.
Unlike the juicy fruits we enjoy each summer, or the dried caryopsis of cereal grains, plants that produce schizocarps have found that procreation works best when each flower produces a number of independent seeds protected by a dried fruit coating. Now you know. Seeing unripe fruit or nuts on the ground, under your tree, can be normal or may indicate a problem. Fruit drop, or June drop, is a natural process that allows a tree to get rid of more fruit than it can support. Fruit drop is common to citrus, apple, avocado, almond, tomatoes, and many other crops. Earlier in the growing season, some trees will rid themselves of unwanted blooms (blossom drop) for the same reason. Some trees, such as loquat, can be messy during this time. Manual fruit thinning works the same way, reducing the quantity of fruit but improving its quality. Fruit drop can also indicate insect pests, disease, or adverse environmental conditions.
Fruit drop caused by insects Black scale feeding weakens the tree, leading to wilting, twig dieback, stunting, and early fruit drop. Mealybug feeding can cause early fruit drop, chlorosis, and sooty mold. Feeding by mites can also reduce a tree’s ability to support a crop, causing fruit drop. Finally, while weevils are better known for burrowing into beans, cotton bolls, and cereal grains, they will also feed on roots, stems, buds, flowers, leaves, and fruit. Often, the first sign of a weevil infestation is leaf wilting, scalloped leaf edges, and early fruit drop. Fruit drop caused by disease Trees will frequently abort diseased or malformed fruit rather than invest water and nutrient resources in fruit that won’t reach maturity. Fruit drop caused by environmental conditions Sudden cold or extreme heat can cause fruit drop, especially in young trees. Strong winds can blow unripe fruit from trees. The most common environmental cause of excessive fruit drop is insufficient irrigation or unbalanced soil nutrients. Almonds and tomatoes are particularly sensitive to feeding and irrigation fluctuations. Pollination and fruit drop Fruit drop can be the result of insufficient pollination. Some trees need genetically compatible neighboring trees they can use for cross-pollination. It can also mean there are not enough pollinators in your area. You can attract more pollinators to your garden by avoiding the use of broad-spectrum pesticides and by installing a wide variety of flowering plants. Or, you can start raising honey bees. Honey bees take up surprisingly little space, boost pollination of nearly all your crops, plus you get honey! Fruit drop and pruning Heavy pruning can leave a tree unable to support the initial crop, resulting in fruit drop. Unless necessary, it is better to leave pruning and tree training for the dormant season. Fruit drop and the soil Low magnesium (Mg) levels in the soil can cause fruit drop, as can high potassium (K) or boron (B) levels. You can’t know what your soil’s nutrient levels are without a soil test from a local, reputable lab. While they look convenient and appealing, over-the-counter soil tests are not yet accurate enough to be useful. The type of soil can also have an impact on fruit drop. Sandy soils are far more prone to fruit drop than heavy clay soil. Don’t panic if your orange tree drops dozens or hundreds of tiny green fruits in May or June. It is normal. Just pick them up and add them to your compost pile. If you notice heavy insect infestations, signs of disease, chlorosis, or wilting, track down the cause and correct it. Remove fallen fruit and mummies to avoid creating a disease triangle or a hotel for pests. How would you like a garden or landscape filled with plants for free? Rather than buying seeds and seedlings, digging furrows, rows, and hills, planting and watering those seeds and seedlings, and hoping for the best, you can let nature takes its course and grow a surprising number of self-seeding vegetables, herbs, and flowers without any help from you. What is self-seeding? Plants classified as self-seeding are usually annuals or biennials that tend to produce a large number of viable seeds, pods, or capsules. These seeds fall to the ground, where they then start a new crop of the same plants (called volunteers) within the immediate (and not-so-immediate) area, during the next growing season. All this productivity occurs without any human intervention. As an added advantage, self-seeding plants provide more pollen and nectar for local pollinators and other beneficial insects than would otherwise be available, and for a longer period of time. Self-seeding plant selection and placement Self-seeding plants come in all shapes, colors, and sizes. Aeoniums, borage, marigolds, nasturtiums, poppies, snapdragons, sunflowers, sweet alyssum, and zinnias and are all self-seeding. Before installing a self-seeding plant, however, be sure to check with your local extension service to make sure it is not an invasive plant. Also, be sure to select a location suitable to long-term growth. You can introduce self-seeding plants into your garden for free simply by tossing a seed head from a mature plant into the area. The seeds will take care of themselves, providing a new crop during the next growing season. Self-seeding vegetables Allowed to follow their natural lifecycle, many popular garden vegetables will bolt and produce hundreds of seeds. While many of these seeds will rot or be eaten by birds and other critters, you will end up with more seedlings than you know what to do with. (Give them to neighbors, family, and friends, Plant It Forward style). A surprising number of vegetable plants readily self-seed, as long as your winters are not too cold: While these offspring are not always true to their parent plants, especially in the case of hybrids (names that include F1), I have found they are always delicious and edible! Open-pollinated (OP) heirlooms are more likely to look, grow, and taste like their parents. I have maintained the same four beet plants, two yellow, one white, and one red, for several years, for seed production. As a result, I have beets turning up everywhere! And the parent plants add changing shapes, sizes, and colors throughout the seasons. Endive and several lettuces are now naturalized in my foodscape. By naturalized, I mean that the plants turn up wherever they take hold. At first, they are low-growing mounds of salad deliciousness. Then, in mid-spring, a central stalk appears, drawing the plant upward in a cone shape that ends up bearing lovely blue and white flowers. After the seeds have been dispersed, I cut the plants off at ground level and feed them to my chickens. Next winter, new crops of endive and lettuce appear like clockwork, with no effort on my part. I transplant some of these volunteers to create lovely borders and accent plants. And they don’t cost me a dime. Self-seeding herbs Many herbs are also self-seeding. Basil, chamomile, chives, cilantro/coriander, dill, fennel, lemon balm, oregano, parsley, and sorrel, are just a few favorite herbs that willful an area without any help from you. Parsley, in particular, is a super seed producer. A single parsley plant can produce the equivalent of 10 seed packets! For free! Self-seeding problems The very characteristics that make self-seeding plants so successful can also make them troublesome. Some self-seeding plants can take over an area, much the way mint plants do. Also, if a plant is prone to certain diseases, such as powdery mildew or blight, or susceptible to insects commonly found in your garden, you might need to incorporate crop rotation to break the disease triangle, or insect life cycle. If you really want them, these self-seeding plants are best corralled into containers and deadheaded frequently. If your self-seeded volunteers turn up in undesirable locations, you can always transplant them into a more suitable or convenient spot, pull them by hand as seedlings, or mow any that turn up in a lawn. If your winters are too cold to allow self-seeding to occur naturally, you can always collect seeds from these abundant producers and use them to start next year’s crops.
Lighten your work load and increase biodiversity in your garden and landscape with self-seeding vegetables and herbs! You can make clones of many favorite plants for free with layering. Layering is a form of vegetative propagation. Unlike other vegetative propagation methods, such as cuttings and division, layering allows the parent plant to continue providing water and nutrients to their offspring as they develop their own root system. This is because they are still attached!
Strawberry runners are an example of natural propagation by layering. The parent plant sends out runners. Where the nodes touch soil, adventitious roots emerge and a new root system begins to develop. As it does, the parent plant continues to support this newly developing clone. Once the offspring are self-sufficient, the runner stem eventually dries up and falls away. Layering uses the same basic idea by pulling a stem downward until it touches the soil at what would have been a leaf node. Coming into contact with moist soil, the plant reprograms that node to become root tissue. Many window sill gardens are populated with herbs, such as rosemary, sage, and lavender, that are easily propagated with layering. In some cases, plants are wounded on one side, to stimulate rooting. In other cases, the stem is bent sharply at the point where it touches the ground. The most critical point in layering is that the soil must be kept moist as the new roots grow. If the growing medium dries out, the process fails. In some cases, this process is complete within the first year. In other cases, it can can 3 or 4 years, so be patient. Some people use rooting hormones (auxins) to speed things up. There are six different types of layering. Air layering Air layering is used predominantly on thick-stemmed houseplants that have become leggy. It is also used to generate new trees and shrubs, including apple, blueberry, citrus, cashew, cherry, fig, kiwi, pear, pecan, and walnut. Stems are slit just below a node and the slit is pried open. The wound is then wrapped with wet, unmilled sphagnum moss and wrapped with plastic, which is tied in place. When new roots fill the moss, a cut is made below the root ball, separating it from the parent plant and replanted elsewhere. Compound (serpentine) layering Compound layering is best suited to plants with flexible stems, such as pothos. Stems are bent into rooting medium in a serpentine arrangement that allows several nodes to begin developing their own root system. Again, some people wound the area that ends up below ground to stimulate rooting. Mound (stool) layering Mound layering, also called stool layering, is used primarily on woody plants to stimulate rooting of new shoots. During the dormant season, the plant is cut back to one inch above ground level. Soil is then mounded over the new shoots as they emerge in spring. This method is best suited for apple and plum rootstocks, and gooseberries. Simple layering Simple layering consists of bending a stem down to the ground and covering it with soil, leaving the last 6 to 12 inches exposed. This tip is bent into a vertical position and staked in place. Wounding the area that ends up underground can stimulate rooting. This method is best suited for hazelnuts, forsythia, and honeysuckle. Tip layering Tip layering is a method commonly used on cane fruit, such as blackberries and raspberries. Tip layering consists of digging a small hole, a few inches deep, and putting the tip of a cane into the hole and covering it with soil. At first, the tip will grow downward. Then, it will complete a U-turn in the soil and emerge aboveground. That bend will develop roots, allowing the new plant to be separated from the parent plant in spring and replanted elsewhere. Trench (etiolation) layering Trench layering, or etiolation layering, is generally used to create fruit tree rootstock and grape vines. In this method, parent plants are planted at a 30 to 40° angle. As new shoots emerge, they are pulled down into shallow trenches, pegged in place, and covered with soil until new roots emerge. Layering is an easy way to make new plants out of existing favorites, without spending any money! Is it true that melons and squash can cross-pollinate? If I plant a lemon tree too close to an orange tree, will the oranges be sour? You’ve heard of cross-pollination, but what does it really mean and do you have to worry about it? Let’s start by reviewing pollination. Pollination and fertilization Pollination refers to the act of pollen, the male genetic information (gametophyte), moving from the anther to the (female) stigma. From there, the pollen grain grows a pollen tube, which makes its way down the style to the ovary. Two sperm cells (gametes) then move through this tube to fertilize female gametes. One male gamete fuses with a female gamete to produce an embryo, while the other fuses with a different type of cell, called a polar body, to form the endosperm, which will feed the developing embryo. [You can think of these two much like the yolk and white of an egg, respectively.] Since two fertilizations are actually occurring, it is called double-fertilization, but I digress. Types of pollination Pollination can occur one of two ways: self-pollination or cross-pollination. Self-pollinating flowers pollinate themselves. Cross-pollination, or allogamy, refers to the way pollen moves from one plant to another of the same species. Wind and insects, such as honey bees, are the main perpetrators of cross-pollination. Natural cross-pollination can only occur within a species (we will not discuss genetic manipulation at the nano surgery level). To give you a clearer idea, consider this: Horses breed with horses. Donkeys breed with donkeys. When a female horse breeds with a male donkey, their offspring, a mule, is nearly always infertile. The same is true in the plant world. This means that zucchini plants can cross-pollinate with pumpkins and other summer squash varieties, but not with melons or cucumbers. This is because squash and pumpkin are both members of the Cucurbita pepo species. In the same way, cucumbers (Cucumis sativus) cannot cross-pollinate with muskmelons (Cucumis melo). Their genetic information doesn’t match up properly. When cross-pollination within a species does occur, the offspring (seeds) are often useless, but it has no affect on the current season’s fruit or vegetable. The only exception to that rule is sweet corn. When varieties of sweet corn cross-pollinate, the current season’s crop will exhibit characteristics of both species. In nearly all other cases, it is the DNA found in seeds that is altered. If you save seeds for next year’s crop (and I urge you to do so), you will grow plants with characteristics of both parent plants. This is how we get many new cultivars with desirable traits or unique properties. The only way to prevent cross-pollination is to keep crops 100 yards or more apart, which probably isn't realistic in your home garden. You can reduce the chance of cross-pollination by keeping plants as far away from each other as possible. The science of genetics owes its start to cross-pollination among common pea plants and a central European monk, named Gregor Mendel, back in the mid-1800’s. As for those sour oranges, they were probably unripe, irrigated improperly, or victims of the Asian citrus psyllid, not the result of cross-pollination.
Most gardeners are familiar with monocots and dicots, but what are eudicots? Let’s find out! Flowering plants (angiosperms) are often categorized by the type of seed they make. You can see these differences with the naked eye. Seeds that come in a single body, such as corn, are classified as monocotyledons, or monocots. Seeds that split into halves, such as peas and beans, have been called dicotyledons, or dicots. Cotyledons are seed leaves. They rarely look like the other leaves produced by a plant. Monocots generally have a single seed leaf, while dicots have two seed leaves. So, how do eudicots fit in? High tech botany Electron microscopes and genetic mapping are drastically changing the way we look at plants. Superficial similarities can no longer be used to classify them. In 1991, an evolutionary botanist, James A. Doyle, and a paleobotanist, Carol L. Hotton, created the term ‘eudicot’ to differentiate between simple, primitive dicots and more modern tricolpate dicots. [How’s that for a word?] Tricolpate is another word for eudicot. Molecular research demonstrated that dicots are not what we thought they were. In fact, dicots are not even included in the new taxonomy! This is because dicots are not all descended from a single ancestor. [Did you know that the study of pollen grains and other spores is called palynology? I didn’t, either.] You will now begin hearing people talk about monocots, eudicots, and basal angiosperms. I would love to tell you that basal angiosperms are those primitive dicots, but it’s not that simple, either. For now, we will simply say that basal angiosperms are an “everything else” collection of flowering plants. If you want to get really technical, angiosperms are now divided into eight orders, instead of two, or three. Here’s the list and any examples I could find:
Eudicots are further separated into two groups: core eudicots and basal eudicots. Core eudicots include members of the sunflower family and the rose family. The basal eudicots are a more eclectic group. All this new information is being resorted using something called the APG IV system. We will discuss all of this in more detail another day. The reason behind much of this reclassification lies in pollen grain grooves. Pollen grooves Using an electron microscope, one can see that pollen grains have distinct patterns or grooves. Eudicots have three grooves, called colpi, that run parallel to the polar axis of the pollen grain. At the base of each of these colpi there are three or more openings, called germination pores. Most other seed-bearing plants, including gymnosperms and monocots, have only one germination pore. This pore is found in a groove called the sulcus. The sulcus is pointed in a different direction from the more visible grooves. Using these new classification tools, we learn that eudicots make up 75% of all flowering plants and 50% of all plant species. At this point, that means there are over 280,000 eudicot species on Earth! Those species include apples, cannabis, figs, olives, oranges, peaches, peas, and plums, along with oaks, maples, and many others.
So, the next time someone starts talking about monocots and dicots, you can set them straight with the latest botanical discoveries! Most of us grew up learning about how pollen sticks to bees as they go from flower to flower, collecting nectar and pollinating many common food crops. But that’s not how it works for your tomatoes and peppers. Instead, they use buzz pollination. Standard pollination
Most flowering plants (angiosperms) have male parts, called anthers, that have pollen on the outside, available to all takers. This pollen held in place by its extreme stickiness. [That stickiness is why you need to use soap and water to get pollen off your face and eyelashes, for those of you who are prone to allergies.] This pollen can be knocked loose by busy pollinators and then carried on the wind, or the pollinators find themselves covered with the sticky stuff, as they move from flower to flower, feeding on nectar and collecting pollen. Dry, dusty pollen Some flowers don’t have sticky pollen. Instead, they have pollen that is dry and dusty. If that pollen was exposed, it would all be gone with the first breeze, most of it never making it to another flower. Instead, these plants have evolved a specialized type of anther, known as a poricidal anther. Poricidal anthers are tubes with tiny openings at one end, but these openings are too small for bees to use. To make matters worse, these plants generally do not offer nectar, so how do they get pollinated? Pollination by vibration Approximately 8% of the world’s flowers are only pollinated when the correct sound wave frequency occurs nearby. When it does, the flower explodes a small dose of pollen into the air, coating whatever is at hand with genetic information and protein-rich food. This is called buzz pollination, or sonication. It gets those names because certain insects that have learned how to buzz at just the right frequency to trigger these plants to share their bounty. These flowers release pollen at frequencies between 40 to 1000 Hz, depending on the species [You can use a tuning fork or an electric toothbrush to try this for yourself.] Scientists believe this arrangement evolved as a means to ensure that each visiting pollinator carries away a smaller portion of pollen (which they are less likely to drop on their way to the next flower) and that those portions are spread out over a greater number of pollinators, and over a wider time frame, for better odds of procreation. How’s that for evolution? Not honey bees Honey bees do not use sonication to get at pollen, but several other bees do. Sweat bees, carpenter bees, and bumblebees all use buzz pollination to get at the pollen held in poricidal anthers. They do this by disconnecting their wings from their flight muscles [I have no idea how they do this!] and vibrating those muscles at just the right frequency. In most cases, this frequency is close to middle C. The force generated during sonication can reach 30 Gs, which is almost more than a human can tolerate! Which plants use sonication? You may be surprised to learn that many common garden plants use sonication. Members of the legume and nightshade plant families frequently use buzz pollination to generate the fruits and vegetables we love. In addition to tomatoes and peppers, other edible plants that use buzz pollination include eggplants, potatoes, peas, blueberries, tomatillos, and kiwifruit. How are your flowers being pollinated? We don’t know why certain flowers tuck themselves in at night, or why some leaves fold themselves together as the sun sets, but we know how they do it. These openings and closings of petals and leaves is called nyctinasty [nik-TIN-as-tee]. Nyctinastic movements are also called sleeping movements.
Options in plant movement While plants are not free to get up and walk around, they do have options when it comes to movement. Some plants follow the sun’s movements across the sky, in a behavior called phototropism. There are also rare individuals who exhibit skototropism by moving away from sunlight. Note that both of those words end with -tropism. Movement is tropic [TRO-pic] if it is in reaction to a source of stimulus. Tropic movement is nearly always growth related and it is dependent on the direction of the stimulus. If a plant’s reaction is independent of the stimuli’s position, it is called a nastic movement. Nastic movements may or may not be growth related. If you see a plant behavior word that ends with -nasty, you will now know that it is a nastic behavior. Nyctinasty is one of those words. Latin bed times We all have our bedtime routines. Some plants do, too. These routine behaviors are called nyctinastic. You just learned that -nastic means movement independent of a stimuli’s position. When it happens because of nighttime, we add the Latin prefix nyct-, which means ‘at night’. Put the Latin for non-directional reaction to nighttime together and you get nyctinasty. Why do flowers close at night? We don’t know. Charles Darwin thought that nyctinasty was used to protect against freezing. Some scientists theorize that it has to do with pollination and reducing competition, or protecting nectar from bacteria and fungal spores. Other possibilities include saving up aroma molecules for when they will be most effective, energy conservation, or as a means to prevent pollen from getting wet. Wet pollen is heavy and insects are less likely to carry as much, potentially reducing pollination rates. Yet another theory is that nyctinastic flowers and leaves close up shop to prevent being eaten by nighttime herbivores. The truth is, we don’t know why. We do know, from laboratory tests, removing the gene that causes nyctinasty results in plants with smaller leaf areas and reduced biomass. We may not know why they do it, but we do know how they do it. How flowers and leaves open and close Several different flowers, such as tulips, dandelions, crocuses, and daisies, and the leaves of many legumes species, open each morning and close each night. Some flowers, particularly the Kalanchoe genus, grow new or longer cells each morning, on the inside of the flower, to open it, and on the outside of the flower each evening, to close it. Other flowers, and most nyctinastic leaves, rearrange fluids within the plant to cause these movements. This movement of fluids is a reaction to changing temperatures and light frequencies. Movements of liquid and light Nyctinasty is triggered within a plant in response to changes in external light, temperature, and humidity, and an internal circadian clock. As the sun sets, light frequencies change and temperatures drop. The shorter wavelength and higher deflectability of blue light gives way to longer, less readily deflected red wavelengths, and lower temperatures. The reduction of blue light triggers blue-green pigments (phytochromes) to rearrange potassium ions within the plant. This rearrangement of ions pulls water along with it, causing turgor. Turgor refers to rigidity that is normally caused by the presence of fluids. So, as dawn arrives and temperatures start to rise, interior cells grow faster, or are inflated with water, to push open your flowers. At days end, outer cells grow longer and faster, or internal cells are deflated, and the flowers close for the night. This is nyctinasty. Allelopathy is the scientific word for chemical warfare in the plant world.
There is plenty of New Age talk about ‘companion plants helping’ each other, but that is not true. Plants do not choose to help their neighbors. [We’ll get into the discussion about ‘plant intelligence' another day.] The truth is, life is a battle. Even in the garden. Competition for resources Most plant roots are constantly competing with neighboring plants for water and mineral nutrients. In the same way, most plants reach for as much sunlight as they can get, regardless of the needs of neighboring plants. That’s life. Its not a decision; its survival. Weeds compete with your garden plants by growing faster. Some plants use tendrils to climb other plants. And some plants use chemicals against neighboring plants and other organisms. What is allelopathy? Allelopathy [al-el-ah-path-ee] is a common way for plants to reduce competition in the immediate vicinity, and to reduce feeding by herbivores. Allelopathic plants actively discharge chemicals through their leaves, bark, and roots, as they decompose, and through other processes. These chemicals can stimulate or inhibit the germination, growth, development, reproduction, and survival of other plants and organisms. Autotoxicity is the flip side of allelopathy. In autotoxicity, plants generate chemicals to inhibit the growth of the same species in the vicinity. The chemicals used in allelopathy always impact other species of plants and organisms. These biochemicals are called allelochemicals. Allelochemicals Allelochemicals can interfere with another plant’s nutrient uptake, photosynthesis, pollen or seed germination, cell division, and even specific enzyme functions. These battles are being fought on the cellular and molecular levels! Because of these effects, allelochemicals are used in commercial agriculture as natural herbicides. For example, the lemon bottlebrush plant (Callistemon citrinus) produces an allelochemical called Leptospermone. Leptospermone is not strong enough on its own to be effective, but a synthetic version, nestorione, is. Nestorione is commonly used to control broadleaf weeds in corn, as well as the crabgrass in your lawn. Allelochemicals are also used as growth regulators, insecticides, and antimicrobial products. One advantage to using allelochemicals is that they tend to not have long term residual effects. Caffeine, and certain flavonoids, tannins, and phenols are all allelopathic chemicals. Species distribution Plants grow where their resource needs can be met. Because of this, allelopathy is an important player in species distribution and population density in the world and in your garden. In some cases, allelopathy gives weeds and invasive plants the upper hand. Nutsedge, garlic mustard (Alliaria petiolata), and spotted knapweed (Centaurea maculosa) all use allelopathy to beat out the competition. The allelochemicals used by garlic mustard have been shown to interfere with native tree roots and their mycorrhizal fungi, which help the trees gather mineral nutrients from the soil. Allelopathy and incompatibility Since some plants leave behind an allelopathic residue, it is a good idea to be aware of the potential for incompatibility when intercropping (succession planting), mulching, using green manure, planting catch crops, or when rotating crops. For example, decomposing straw has been shown to suppress weed growth, as well as reduce the number of pests and diseases found in an area, because of the allelochemicals contained in the straw. As it decomposes, it also improves soil structure and soil fertility. At the same time, decomposing straw temporarily increases the carbon-to-nitrogen ratio, so you may need to supplement the area with nitrogen. Catch crops, planted to protect the soil from erosion between major crops, are an excellent way to protect your soil, but they also introduce allelochemicals that may interfere with the next crop. One sorghum-sudangrass hybrid (Sudex), in particular, can kill 50 to 75% mortality of your tomato, broccoli, and lettuce plants! Allelopathic plants Many common plants use allelochemicals. Black walnut is the most notorious, but the story isn’t (as is often the case) as simple as it is made out to be. Black walnut (Juglans nigra) produces several allelochemicals which are said to block everything from growing underneath. This is simply untrue. The chemicals involved, and the interactions, are far more complex than that. Onions, beets, squash, melons, carrots, parsnips, beans, yarrow, stonecrops, and corn can all be grown near a black walnut tree without any problems, according to the PennState Extension. At the same time, blackberries, raspberries, blueberries, asparagus, eggplant, peppers, potatoes, and tomatoes do not grow as well when planted near a black walnut tree, according to the University of Illinois Extension. Allelopathy and agriculture Most of the research regarding allelopathy focuses on commercial agriculture. It tells us that rice, some Eucalyptus species, and the Tree of heaven (Ailanthus altissima) all use allelochemicals. It also demonstrates that rye mulch significantly reduces broadleaf weed growth, and that growing mung beans in a corn field reduces crop yield, while growing tobacco in the same corn field increases corn production. Allelopathy in the garden This is a highly complex issue that cannot be watered down very far before everyone is simply guessing. That being said, I have been able to glean the following useful information for the home gardener:
If you suspect that two plants are incompatible, simply conduct an online search, using both plant names and the word allelopathy. If there is any research available, please let us know in the comments section! Most of the ‘rules’ associated with allelopathy have been developed with large-scale agriculture in mind. They are diluted by all the other factors occurring in your garden and compost pile, so take it with a grain of salt. This information is not going to stop me from composting my healthy pea plants, but it will make me more aware of my plant choices, when it comes to cover crops, crop rotation, and catch crop planting. Most people know that ‘deciduous’ refers to trees that lose their leaves each year, but there is more to the word and the process than meets the eye. When a plant no longer needs a flower’s petals, those petals are allowed to fall away. When fruit becomes ripe, it is also allowed to drop. This act of ‘allowing to fall away’ is at the heart of deciduousness. Did you know that a deer’s antlers and your own baby teeth are also considered deciduous? Pros and cons of deciduousness
Unlike evergreens, deciduous trees and shrubs, and some herbaceous perennials, lose their leaves each year. This is called abscission. In the Northern and Southern hemispheres, leaf drop normally occurs in autumn or early winter. In tropical regions, deciduous plants lose their leaves during the dry season. In each case, leaf loss occurs at a time when having leaves is not in the plant’s best interest. For example, broad-leafed hardwood trees might collect too much snow or ice in winter, causing limbs to break off, leaving open wounds, while tropical plants are unable to maintain heavy leaf cover without rainfall. This annual leaf drop is believed to be a mechanism by which some plants interrupt pests and disease triangles. It also means a plant must have enough food stored to last through the winter and to begin growing again in spring. Another benefit of abscission is related to something called cavitation. Cavitation refers to times when water tension within a plant becomes so great [think rainy season] that the sap vaporizes within the tree and the oxygen held in that water expands rapidly enough to cause a loud ‘crack’ - you may have heard this, if you spend any time in forests. The problem with cavitation is that it damages the xylem. Plants can usually repair this damage, but not aways. One way deciduous plants protect themselves against cavitation is by dropping their leaves, which, in turn, allows them to have larger xylem vessels. These larger xylems allow deciduous plants to take up more water than evergreens in the summer months. The chemistry of deciduousness During spring and summer months, deciduous plants are busy producing chlorophyll, a green pigment. Shorter days (or drought stress) trigger plant hormones (auxins) to reduce chlorophyll production and to start drying the connection between the stem and petiole of each leaf. In some cases, the plant also withdraws the nitrogen and carbon held in those leaves for use in spring. Lower levels of the green pigment are what allow us to see other colors. Some of these colors, the yellow, brown, and orange carotenoids are always present, while red and purple anthocyanins are produced in autumn, as sugars become trapped in the leaves. These changes are triggered by shorter days and cooler nights. In areas without those conditions, the leaves simply dry up and fall off. Deciduous trees and shrubs Common deciduous trees include almond, pomegranate, quince, apricot, nectarine, peach, olive, persimmons, plum, fig, pear, walnut, and apple. Your grapes, kiwifruit, blackberries, raspberries, strawberries, and blueberries are also deciduous. In fact, nearly all fruit and nut crops occur on deciduous plants, citrus being a notable exception. Winter is the best time to prune deciduous trees. [Except apricot and cherry, due to eutypa dieback.] The absence of leaves makes it easier to see the true structure of deciduous trees and shrubs, allowing you to see and remove dead, diseased, crossed, and poorly placed limbs. Winter is also the best time to apply dormant oil, to control many pests, such as scale. Have you ever been to a family reunion and wondered how that one cousin could possibly be related to everyone else? Well, it happens in plant families, too. Learning about plant families can help you generalize about plant care, potential problems, and best practices. It also makes you sound really smart when talking with others about their garden and landscape struggles and successes. If nothing else, learning about the basic edible plant families can help you make the best choices when it comes to crop rotation. Amaranth Family (Amaranthaceae) - The traditional amaranth family includes quinoa, lamb’s quarters, and, well, amaranth. Recent genetic testing showed us that chenopods, such as spinach, beets, goosefoot, and chard, are also members of this family. If you look at the prolific way seeds are produced, this should come as no surprise. [A while back, I allowed a few beet plants to go to seed. I now have beets coming up all over the place!] This group’s petalless flowers and deep-reaching roots often thrive in less than desirable soil. These crops need to be watered deeply and they do not perform well in acidic soil. Leaf miners are the most common pest. Cabbage Family (Brassicaceae/Cruciferae) - The cabbage family, also known as a cole crop, includes broccoli, cauliflower, turnips, kale, Brussels sprouts, collard greens, radishes, mustard, and watercress. They are identified by their four cross-shaped flower petals, with six stamens, and long, narrow fruit/seed pods (siliquose). Most of these plants have a distinct sulfur-like odor. These are usually cool weather crops that prefer neutral or slightly alkaline soil pH. Clubroot can become a problem if crops are not rotated Cashew Family (Anacardiaceae) - Accessory fruits and drupes give us delicious nuts, tropical fruits, paint varnish, and nightmarish cases of poison ivy, poison oak, and poison sumac. While you may be able to grow your own cashews, depending on your Hardiness Zone, you may want to read more about it before you try. Citrus Family (Rutaceae) - The flowers of this family, which includes citrus trees and rue shrubs, tend to divide into four or five parts and they usually have a strong smell. Grapefruit, kumquat, lemons, limes, mandarins, and those tiny delicious, loose-skinned oranges (calamansi) are all members of this family. Grain Family (Poaceae) - While processed grains have been getting a bad rap lately, the grass family tree has grown alongside ours since the Agricultural Revolution began, some 10,000 years ago. The grain family includes wheat, corn, rice, oats, rye, sorghum, millet, grasses, bamboo, and barley. They are heavy feeders that need extra nitrogen. Legume Family (Fabaceae) - This fabulous group has figured out how to capture atmospheric nitrogen, making them an excellent choice for green manures and cover crops, as well as the dinner table. The legume family includes peas, beans, cowpeas, peanuts, soy, fava beans, alfalfa, and lentils. Clover is also a member of the legume family. Adding too much nitrogen to these plants will stimulate vegetative growth, rather than an edible crop. Most of these crops lose some of their nitrogen-fixing ability after they have been transplanted, so direct sow when possible. Mint Family (Lamiaceae) - The leaves of this mostly perennial family all feature glands that produce aromatic oils. Common members of the mint family include lemon balm, sage, thyme, oregano, lavender, basil, marjoram, rosemary, and savory. Many of these plants feature four-sided stems and they can grow pretty much anywhere. They tolerate drought and poor soil, and most of them tend to spread out over an area. Nightshade Family (Solanaceae) - While parts of these plants can be toxic, we have long enjoyed the tomatoes, potatoes, eggplants, tomatillos, bell peppers, chili peppers, and tobacco that are part of this family. Flowers have five petals, leaves are alternate, and the fruit is a berry. These plants are prone to verticillium wilt and fusarium wilt when crop rotation is not used. Nematodes can also be a problem. These plants love moist, nutrient-rich soil. Onion Family (Liliaceae) - Members of the onion family usually have long, vertical leaves, a leafless flower stalk (scape), and flowers with six petals (or multiples thereof). Leeks, garlic, chives, shallots, and asparagus are all members of the onion family. [Who figured out that asparagus is a member of this family?] Parsley Family (Apiaceae/Umbelliferae) - The umbrella-shaped flower clusters of this family make them easy to identify. Carrots, coriander, celeriac, celery, and fennel, along with parsley, are all cool season crops. They are slow growers that readily cross-pollinate. These plants do not like heavy, clay soil, which makes them a good choice for raised beds and containers, depending on each plant's rooting depth. Rose Family (Rosaceae) - This one may surprise you. Along with roses, members of this family include pomes, such as apples and pears, blackberries, raspberries, cherries, and strawberries. This family also includes stone fruits, such as apricots, plums, almonds, peaches, and nectarines. Members of the rose family all have alternate leaves and single or composite flowers, that tend to be pinkish. Squash Family (Cucurbitaceae) - This family is a thick-skinned group that grows on vines and keeps its seeds in a line down the center of their fruit. The squash, or cucurbit family is made up of melons, pumpkins, cucumbers, gourds, and the inevitable zucchini. These plants love hot weather and many of them have protective bristles. These plants grow quickly and need regular irrigation. Powdery mildew and blights are common problems, along with flea beetles and cucumber beetles. Sunflower Family (Asteraceae/Compositae) - This very large family of plants has compound flowers and shallow roots. Member of the sunflower family that frequently make their way to the dinner table include artichokes, sunflowers, marigolds, lettuce, cardoons, chamomile, tarragon, chicory, escarole, and salsify. Dandelions are also part of this family. Most of these plants do not perform well in heavy clay, so be sure to regularly top dress the soil with aged compost. These plants have very few pests and they tend to attract pollinators and other beneficial insects. This list is, by no means, exhaustive, but it provides a good starting point.
All plants grow toward sunlight, except when then don’t. In nearly all cases, plant stems, vines, and bines grow upward, reaching for the sun’s energy. Plants deprived of sunlight will often grow longer than they can support, in an effort to reach that energy source. This is called etiolation. But, sometimes, it is better for a plant to grow away from sunlight. This behavior is called skototropism.
The dark side
Light levels are pretty dim at ground level in a thick jungle. If a vine does not find a tree to climb, it will die. If it heads toward visible light (an opening in the canopy), it will never find a tree to climb. Instead, these vines must grow toward the darkest place they can find (the base of a large tree) in order to find something big enough, strong enough, and tall enough, to provide support. What’s really interesting, is that larger trees attract more vines, while smaller trees attract less vines. There are even mathematical formulas that describe skototropism among certain jungle seedlings! Once a climbing plant has found a support structure, the skototropism behavior is turned off and upward growth (phototropism) begins in earnest. [Some scientists believe that roots grow down because of skototropism, while others believe it is something called gravitropism. You decide.] Reindeer love it and your trees may wear it, but what is lichen? Lichen is primitive and complex, but it is not a plant. Nor is it a fungi. Well, not exactly. Lichens are one of Earth’s more bizarre life forms. You know it when you see it, but that’s usually as far as it goes. Before we learn the secrets of lichens, let’s review some basic plant and fungi facts that will help us understand lichens better. Plants and fungi Some 500 million years ago, when life was sorting itself out here on planet Earth, tiny bacteria, called cyanobacteria, learned how to absorb the sun’s light energy and convert it into food. These talented bacteria were swallowed up by primitive plant cells and later evolved into chloroplasts. Chloroplasts are the organelles within plants where photosynthesis occurs. Fungi - Fungi are not plants. They are their own kingdom and they do not have chloroplasts, which means that they cannot produce chlorophyll or perform photosynthesis. Fungi get all their nutrients from decomposing organic material. Algae - Algae are also not plants. And they, too, have their own kingdom (Protista). Algae (or alga, if you only have one) come in many different colors. Algae contain chlorophyl but they do not have leaves, roots, true stems, or vascular tissue. Bacteria - Bacteria are one-celled microorganisms that lack a nucleus. [Did you know that a single teaspoon of soil can contain up to one billion bacteria?] Most bacteria are parasitic decomposers. Many are beneficial. In fact, we could’t digest our food without the help of bacteria in our gut. Lichens - Lichens are not plants and they do not have roots, stems, or leaves. If you cut a lichen in half, you will often see distinct layers. It’s what makes up these layers that make lichens so strange. What are lichens? Lichens are actually two separate organisms living in a symbiotic relationship. A lichen is a fungi combined with either algae or those cyanobacteria mentioned earlier. The fungi is the boss and it dictates the way a lichen functions and grows. The algae and the cyanobacteria perform photosynthesis, providing the combined unit with food. This means that the lichens on your tree are generally not causing any harm. Heavy lichen growths can interfere with light and gas exchanges. Lichens retain moisture and can survive complete dehydration. Parts of a lichen While not obvious to the naked eye, lichens have distinct parts:
Types of lichen There are several different types of lichen, based on their growth behavior:
Lichen reproduction Lichens reproduce both vegetatively and sexually. Vegetative reproduction can be as simple as breaking off a piece of an existing lichen. All of its natural processes will continue. Bacteria reproduce through cell division (mitosis). The fungal portion of lichen can produce fruiting bodies that release spores which take to the wind and land elsewhere. These spores must mature and connect with suitable bacteria to become a lichen. Since there are several different types of fungi that can become a lichen, the individual structures may vary. Approximately one-fourth of all fungi are tied up in this sort of arrangement. These fungi are referred to as lichenized. Because of this conjoined arrangement, algae is able to exist all around the world, converting carbon dioxide into the oxygen we breathe. Lichens are also able to absorb pollutants and heavy metals from the atmosphere. You can learn more at the United States Forest Service National Lichens & Air Quality Database and Clearinghouse.
What sort of lichens are growing in your garden? Does ‘decurrent’ mean that your fruit and nut trees have gone out of fashion?
No, that would be démodé and left entirely to personal opinion. Decurrent may refer to a tree's (or a leaf’s) overall growing behavior, or it may mean you have some pruning to do. Decurrent trees Trees are described as either decurrent or excurrent. Excurrent trees have a single trunk all the way to the top. Pines and most other gymnosperms are examples of excurrent trees. Most shrubs and angiosperm trees are decurrent. Decurrent trees get most of their structure from scaffold branches. Scaffold branches are lateral (side) branches that are no more than half the diameter of the main trunk (less than one-third is even better). Most fruit and nut trees are decurrent. The decurrent growth is caused by weak apical dominance. Apical dominance simply means that the main central stem grows faster than everything else. Decurrent leaves Some leaf blades wrap themselves around a length of stem. These are decurrent leaves. The grass in your lawn is decurrent, as is mullein. The gills of a mushroom are also described as decurrent because the gills of many varieties are attached downward on the stem. Pruning decurrent trees Decurrent trees should be pruned in such a way that the main trunk is kept to approximately two-thirds of the tree’s overall height. The trunk, or central leader, should not be topped or headed back unless necessary to control for size. Secondary trunks are removed and the overall structure of the tree is developed with scaffold branches. Decurrent trees with multiple trunks are more prone to storm damage, but they tend to grow that way naturally. These extra trunks should be removed. Decurrent branches Branches that grow upward get more sun and tend to be mostly vegetation (leaves). Branches that are predominantly horizontal produce the most fruit. Decurrent branches, the ones growing from the bottom of supporting branches, tend to lose vigor and generally only produce small fruit. This is not the same thing as a heavily laden branch being pulled downward by the weight of its harvest. Decurrent branches should be removed as soon as they are seen, taking care to not damage the branch collar. Decurrent branches can also increase the chances of torn limbs, if the crop is particularly heavy. Removing these downward facing branches will redirect your tree’s efforts toward the more productive branches. Decurrent is not the same thing as those squash plants that someone forgot water last August. That’s wilting. Decurrent is a growing behavior, not a dying behavior. “I can give you a cutting of that, of you like.” Well, what are cuttings and why would you want one? Most of us have seen how the leaf of a Jade plant (Carassula argontea) can be plucked from a parent plant, stuck in some soil, and the leaf becomes an independent plant. Cuttings can be from leaves, roots, or stems. Before we learn about each of these propagation methods, let’s find out how a piece of a plant can become a whole plant. How do cuttings work? Being able to produce a new plant from a piece that was cut off is due to two conditions called totiopotency and dedifferentiation. Dedifferentiation means a specialized cell can return to a state of undifferentiated, meristem tissue, which can then become any other cell found within that plant. Totiopotency, or cell potency, means that every cell contains all of the genetic information needed to generate the entire plant, much like the supreme personage of Element Five movie fame. This means that, in theory, a single cell can be used to regenerate a new, identical plant. Of course, outside of the lab, your chances of success are much higher if you have many, many cells to work with. Let’s see how the different methods of cuttings can be used to propagate your plants. Leaf cuttings The Jade plant mentioned above is an example of a leaf cutting. In that case, new roots, and then new stems, are formed at the wound site, after it has had a chance to dry a little. Most plants cannot be generated from leaf cuttings. While a few spindly roots may appear, they quickly rot and die. Leaf cuttings are best suited to succulents, cacti, and a handful of popular tropical houseplants. These plants can form new roots at the base of the petiole, or leaf stem, from the axillary (or lateral) bud, or from the leaf veins. There are four types of leaf cutting:
Stem cuttings There are three basic types of stem cuttings: herbaceous, softwood, and hardwood. Brand new growth is “green” or herbaceous, softwood is slightly more mature, and hardwood is woody and fully mature. [This is not the same thing as hardwood and softwood trees.] Hardwood is the most difficult to propagate with cuttings. Some plants, such as mint, seem to spread whether you want them to or not. Very often, these plants are well-suited to propagation by stem cuttings. Herbaceous stem cuttings are taken in spring. Make sure that your stem cutting contains both nodes (where leaves and buds occur) and internodes (the spaces between nodes), since some plants generate roots at one, while others root at the other. If you have both, it won’t matter. Tomatoes, basil, sage, and many other herbaceous plants can be propagated this way. Hardwood cuttings are taken from fig, grapes, pomegranates, quince, blueberries, mulberries, some plum varieties, currants, kiwifruit, and gooseberries, while they are dormant. There are three types of hardwood cutting: straight, heeled, and mallet. Straight hardwood cuttings are simply 6 to 15 inch segments cut from near the end of pencil-width, one-year old branches, using a flat cut, removing any unripened green growth from the terminal end using an angled cut. [There is not enough food in the growing tip to be useful.]
At the proximal, flat-cut end, remove some of the outer bark, exposing a little of the cambium layer (light green). If you are using rooting powder, do so at this time by dipping the exposed area in the powder, tapping the branch gently to knock off the excess, and then insert the stem in a hole created with a dibber (or a pencil). This prevents the rooting powder from being scraped off. The stem should be submerged in the rooting medium, leaving only the top bud above soil level. Mallet and heel cuts are used for the most difficult to propagate plants. Heel cuts include a portion of the parent branch, while mallet cuts include small segments from the parent branch. Softwood cuttings are more likely to succeed when taken in mid-summer. Softwood plants include perennials, such as blueberries, rosemary, thyme, sage, oregano, lavender, lemon balm, as well as some ground covers, vines, shrubs and trees. You know how amazing it is that roots always know to go down and stems tend to go up? Well, when you take a stem cutting, the bud that was closest the parent plant’s center (proximal end) will become the roots, while the end that was farthest away (distal end) will become stem tissue. This is due to a behavior called polarity, caused by auxins within the stem. (Auxins are plant hormones.) Simply turning them upside down does not change this behavior, so plant accordingly. Also, because buds contain the auxins needed to stimulate root and stem growth, make sure there are buds on your stem cuttings, and that the area around the bud is not damaged. If there are any leaves present, let them stay, as long as they are not too big. Leaves are a source of auxins and other cofactors used to stimulate root development, as well as food through photosynthesis. If the leaves are too large, they can be trimmed down with a pair of scissors. Root cuttings Many people mistake the spreading habit of plants produced by stolons and rhizomes as a form of propagation by cuttings, but this is not accurate. Those plants produce roots and stems at broken points as a natural growth behavior. Root cuttings, on the other hand, produce new stems and roots at the pericycle, which is the area between the epidermis and the phloem, near the cambium layer. Adventitious roots are more likely to occur when root cuttings are taken from juvenile plants than from older plants. Plants propagated from root cuttings may exhibit new characteristics (phenotype) due to normal genetic behaviors of different layers of cells (periclinal chimera). In English, this means that root cuttings taken from a thornless blackberry will produce blackberry bushes with thorns. Large rooted plants - Root cuttings are generally take from 2 and 3 year old plants during the dormant season. To help you remember which end of the root is the top, make the upper cut horizontal, while the lower cut is angled. You will need a segment that is 2 to 6 inches long. Store your root cutting in moist peat moss, sand, or sawdust at 40°F for 3 weeks. Then, insert the entire root cutting into the medium, with the flat, top edge level with the rooting medium. (horseradish) Small rooted plants - You will only need 1 or 2 inch sections of these roots for cuttings. Then, simply lay them on the rooting medium, about 1/2 an inch deep. (geranium, bleeding heart ming aralia) Rooting factors Plants are classified according to their rooting ability: rapid rooting, auxin-requiring, or cofactor-deficient. Rapid rooting plants have everything they need and will begin rooting right away. Auxin-requiring plants need help from a root compound that contains, you guessed it, auxins. Some plants contain root inhibitors and they lack the rooting cofactors. Simply applying rooting hormone will not help.These plants are really tough to grow from cuttings. Success factors There are many factors that have an impact on whether or not your cuttings will survive and thrive. These factors include environmental conditions, the physiological state of the plant cutting, and the rooting media or soil.
Since each plant has its own Perfect World, you will have to research each species individually, but they are all more likely to succeed when cuttings are taken first thing in the morning. How to take a cutting To ensure your cuttings can survive the process, always use a very sharp knife or razor that has been sterilized in rubbing alcohol. This will prevent the spread of disease to the cutting. Tearing or using shears to remove cuttings does not leave a smooth edge and plants tend to be unable to heal quickly enough to start growing. Remove any existing flowers and flower buds. If leaves are particularly large, they can be reduced in size to allow for better air flow while still allowing photosynthesis to occur. To speed the rooting process, you can dip the cut end in rooting powder, which may or may not contain a fungicide. Cuttings can be an excellent way of continuing the line of a preferred plant without spending any money. Since plants are unable to relocate, they must adapt to their surroundings. Before we start exploring plant adaptations, let’s make one thing clear: plants (as far as we know) do not ‘decide’ to do anything. Genetic mutations are happening all the time. In some cases, a mutation occurs that makes a living thing better suited to its surroundings. Plants that develop beneficial mutations live long enough to reproduce, while those that don’t, well, they don’t. It’s a basic rule of evolution: What works, is. What doesn’t, isn’t. Types of adaptations Plant adaptations are categorized as behavioral, physiological, or structural. These adaptations can make a plant better suited to its environment, more likely to get the food and water it needs, or better able to ensure genetic survival of its species.
The easiest way to see a variety of plant adaptations is to look at the ways plants adapt to their surroundings. Depending on where a plant grows, certain adaptations can come in handy. Biome adaptations Biomes are large, naturally occurring communities of plants and animals found in a specific environment. Each biome has its own characteristics that require different adaptations for a plant species to survive and thrive. Deserts - Scorching heat makes water retention a priority. Succulents store water in their leaves; waxy cuticles reduce water loss; leaves stay small; flowers bloom quickly after a rain; deep roots find underground water; fast-acting surface roots collect dew and rainfall before it evaporates; hairy leaves help shade the plant; spines reduce grazing; and blooming at night attracts pollinators that are not active during the day. Grasslands - Hot summers, cold winters, and the threat of fire encourage adaptations such as: deep, extensive root systems; narrow leaves that retain water; soft stems that bend in the wind; and plants that grow from their crown, rather than from stem tips. Taiga, or boreal forests - Cold winters, swampy soil with poor drainage, and areas of permafrost make being an evergreen a good idea: waxy, needlelike leaves lose less water; drooping branches shed snow more easily; and coloration is usually dark, to absorb more heat. Temperate deciduous forests - Four distinct seasons and plenty of rain make for tall trees: thick bark; shade-tolerant shrubs; flowers that bloom early in the season, before tree leaves block sunlight; broad tree leaves capture plenty of sunlight and then are dropped before snow can weigh them down. Temperate rain forests - Heavy rain and steady, cool temperatures make growing slow business: many plants, such as moss, grow on other plants, helping them reach sunlight; tree seedlings often start growing on dead nurse logs, which provide added nutrients. Tropical rainforest - Heat and heavy rain are a recipe for pests, diseases, and leaching: these plants use rapid growth, climbing growth behaviors, or other plants (epiphytes) to get at the sunlight; trees tend to have smooth bark, making it difficult for vines to climb and choke them; drooping leaf tips reduce standing water; and above ground roots provide added stability. Tundra - Dry, cold conditions make it a good idea to stay low and close to the ground for warmth: fuzzy stems and leaves provide wind protection; dark flowers absorb more heat. Water - Plants living in water tend to have flexible stems and floating leaves and seeds. Nutrient scarcity In some situations, plant nutrients are scarce. Some plants, such as legumes, are able to harvest nitrogen from the atmosphere, while other, such as Venus flytrap and pitcher plants, attract and trap insects for their food. How bizarre is that? Bizarre adaptations Now for the really fun stuff. These plants have managed some extreme adaptations. We will start with the Welwitschia, or onion of the desert. Found in Namibia, the Welwitschia has leaves that can be 13 feet long and a stem that can grow to 6 feet in height and over 20 feet in diameter! This plant can live for up to 1500 years, even if it only gets rain every 4 or 5 years. Another adaptive oddity is the Corpse Plant (Rafflesia Arnoldii). The Corpse Plant produces the biggest (up to 3 feet across) and stinkiest (hence the name) flower known. Another stinky specimen of similar name, the Corpse Flower, or carrion flower (Amorphophallus titanum) may look lovely, but the stench is said to be awful. Those smells may attract pollinators, but I think I’ll pass on trying them in my garden!
While longer daylight hours may energize us, it is warmer temperatures that really get plants and insects going.
During colder winter months, most plants and insects don’t do much. It isn’t until a certain number of days are spent within a range of warmer temperatures that growth can resume. This combination of time and temperature is called physiological time. The physiological time needed by any particular organism stays relatively the same, much like the chilling hours required of certain fruit and nut trees to produce a good crop. Physiological time is expressed in degree-days (°D), also know as growing degree-days (GDD). How are degree-days used? The number of degree-days needed for any particular species to move from one developmental stage to another (phenology) is still being researched, but you can this information to help you predict germination, vegetative growth, bloom times, and harvest time. Degree-days are also very important when using pheromone traps and other pest controls for things like San Jose scale. Beekeepers are beginning to look into degree-days as a way to predict colony lifecycle. Temperature thresholds Generally speaking, degree-days needed by warm weather crops are those with temperatures between 50°F and 95°F, while cool weather crops have a low end temperature of 40°F. These thresholds can also vary by individual species. When temperatures drop below the lowest temperature, called the baseline, development stops. Above that range, development slows or cuts off altogether. Baselines of common garden plants: 35°F - onions 38°F - carrots 39°F - strawberries 40°F - asparagus, barley, beets, broccoli, collards, lettuce, oats, peas, potatoes, rye, wheat 45°F - squash, sunflowers 50°F - beans, corn, musk melons, peppers, sorghum, tomato 55°F - cucumber, watermelon 60F - eggplant, okra, sweet potatoes Calculating degree-days There are several different models used to calculate degree-days, but, here in the U.S., they all boil down to the same basic idea. Degree-days are calculated first by adding that day’s high and low temperatures and diving by 2 for a mean temperature for the day. A plant’s baseline temperature is then subtracted from that mean temperature, for a number of degree-days counted for that day. For example: High 84°F Low 54°F (84 + 54) / 2 = 136 / 2 = 66 mean temperature Base 50°F 66 - 50 = 16 degree-days Unless you really enjoy this sort of thing, you do not need to worry about calculating degree-days for yourself. Agricultural researchers have already done that work for you. You can look up your local degree-days using the UC Davis CA weather data (assuming you live in California). You can also try OSU’s Croptime calculator. Or, you can invest in your own weather station and generate a more accurate, customized model. Since each garden and neighborhood is its own microclimate, the degree-days reported are only estimates anyway, but these estimates can give you the advantage when controlling pests and caring for your plants. Degree-days to maturity Most seed packets offer a “days to maturity” number. This number is a statistical average spread out over the entire country. Factor in things like local climate, drought, pests, and disease, and you can see that these averages are only marginally useful. You can use weather station information to generate your own, more accurate days to maturity measurement. Here are the degree-days needed by a few common garden plants and pests to reach maturity:
What surprises me is that the number of degree days for common garden plants, pests, and diseases is not yet readily available. I’ll keep you posted as the research is published. Saving seeds is a great way to save money and encourage plants that thrive in your microclimate. People have been saving seeds for over 12,000 years. Once you have plant varieties that work for you, there is often no need to continue buying seeds. Your plants will produce them for free! There are three steps to successful seed saving: selection, timing, and storage. But, before we learn how to save seeds, we should review some basic information about plant reproduction. Plant reproduction Plants produce seeds to pass on genetic information. Those seeds are produced when a female gamete is pollinated. The way pollination occurs, and the plants involved, make a big difference in what the resulting seeds will become:
Seeds produced from plants pollinated by insects, wind, and other natural mechanisms are called open-pollinated (OP). Open-pollinated seeds are more genetically diverse, which helps plants adapt to new conditions. As long as cross-pollination between a different variety does not occur, open-pollinated seeds will produce similar offspring. That being said, bees can travel for several miles, carrying pollen, so there is no guarantee of avoiding cross-pollination unless you keep your plants sequestered in a greenhouse. The nice thing is, you may end up with something more beautiful, better adapted, or tastier than what you had before! If not, you can always add it to the compost pile and try again next year. So let’s get started! Select seeds to save The first step is to identify which plants in your garden are open-pollinated. You can use seed packets, plant labels, and online receipts to track down this information. Personally, I have a plastic tub that contains all of my seeds and seed packets, so everything is in one place. I put seeds in envelopes and then write what it is, and where and when it was planted, on the envelope. It really helps me keep track of things! Once you have figured out which of your plants are open-pollinated, pick the ones that grow well and taste the best. Be sure to save seeds from more than one plant of a particular variety, to maintain that healthy diversity. Do not save seeds from plants that lack vigor or flavor. One trick I use is I attached colored ribbons to plants that I plan to save seeds from, using different colors to indicate early or late producing. A note on GMOs and other seed patents: private corporations have invested in and own this genetic information. It is illegal to save, use, sell, or trade these plants and their seeds, according to the World Trade Organization’s agreement on property rights. Consider yourself warned. Seed harvesting
Leave the very best fruits to ripen naturally on your chosen plants. With tomatoes and peppers, you can even let them get a little wrinkly before picking. Then, open the fruit and remove the seeds. With tomatoes, I just drop the gel-covered seeds onto a paper towel and spread them out a little. Next, I write the name of the plant variety on the paper towel and allow it to dry completely before storing. Pepper seeds are just scraped off the white pith and allowed to dry. Peas and beans should be allowed to dry completely on the vine. Keep in mind, however, that this tells the plant it has completed its reproductive cycle and production may begin to lag. Seeds from plants such as lettuce, carrots, and onions can be collected using paper bags tied over the top of the pollinated flower heads. Generally, I do not save those seeds. Instead, I simply let them do their thing naturally. As a result, I have onions, carrots, and lettuces growing all over my property, with zero effort on my part! Storing seeds Many people suggest storing seeds in glass jars or plastic bags, after the seeds have dried completely. Unless you are absolutely sure there is no moisture, it is a good idea to include one of those silica packets you find in shoe boxes and jerky bags, just wrap it in a piece of tissue. As you already saw, I use paper envelopes stored in a secure, but not airtight plastic container, that is kept outside year round. My thinking is, this exposes the seeds to as much of the local, natural environment as possible, weeding out the weak through natural selection. However you store your seeds, be sure to label them right away. It helps if you include the plant name and variety, plus the date the seeds were harvested. Older seeds lose their vigor, so you will want to use seeds within one year for the best results. Seeds need to be kept in a cool, dry, dark place to avoid germinating at the wrong time of year or when you’re not looking. Disease control Seed surfaces can be contaminated with bacteria, fungi, viruses, spores and nematodes. The inside of a seed can also host pathogens. This is why it is so important to only collect seeds from healthy plants. In a study conducted at UC Davis, it was found that pumpkins exhibiting surface lesions of Fusarium wilt (Fsc 1) could still be used as a safe seed source, while pumpkins that were infected all the way into the seed cavity could not. Saving your own seeds allows you to encourage the plants that thrive in your garden. Over time, you may even create your own heirloom varieties! In some plant descriptions, you may read that they ares “strongly accrescent” or “scarcely accrescent.” What does that mean? Accrescent refers to a plant or plant part that continues to get larger as it gets older. Most plants and plant parts are hardwired to stop growing once they reach a specific size. These sizes vary by individuals because of irrigation, nutrition, temperatures, sunlight, pests and disease, but the estimates are generally true. Other plants, or plant parts, never stop growing in size, or they may continue to grow beyond the rest of the plant until some developmental stage is reached. Degrees of accrescence The degree to which a plant is considered accrescent can vary quite a bit. In some cases, only the peduncle, or flowering stem, is accrescent, and then only until the flower reaches maturity. These plants are rated as slightly accrescent. Most commonly, it is the calyx that is accrescent. Calyx, or sepals, are the green modified leaves that surround the base of a flower. The papery covering seen on tomatillos (Physalis philidelphica) is an example of moderate accrescence of the calyx. When the calyx stops growing, your tomatillos are ready to harvest. Plants that are rated as “strongly accrescent” take the challenge to grow very seriously. These plants just keep getting bigger. Giant sequoias are an extreme example of accrescence. Understanding accrescence can help you identify unknown plants. It can also help you to know when to harvest your tomatillos!
Acaulescent is the word used to describe plants with no visible stem. [It is pronounced a-kaw-LE-sent.] Most plants have one or more central stems that support the aboveground portion of the plant. These plants are called caulescent. Acaulescent plants do not appear to have stems. Instead, these plants tend to grow their leaves close to the ground in a clustered, rosette, or whorled pattern, common of many succulents. Some acaulescent plants can get quite tall, but these are generally still leaves growing out of the ground. Now, don’t be fooled. Acaulescent plants still have a stem, it’s just extremely short and the internodes (the spaces between nodes) are densely contracted. How acaulescent plants grow You may be thinking that many succulents have long stems that support flowers, and you would be right. Those inflorescence axis stems are called peduncles. Unlike a trunk or central stem, these growths are purely reproductive and not structural. Many acaulescent plants have modified underground stems, such as rhizomes, bulbs, or tubers. Instead of sending up a central stem, acaulescent plants put leaves out from the crown. Some of these leaves are thick and mucilaginous, as with succulents, while others are the familiar broad leaves of many tropical plants. The stems you do see attaching the leaves to the crown are actually part of the leaf. These leaf stems are called petioles. Examples of acaulescent plants Aloe, agave, and yucca are popular acaulescent plants. Most bulbs, including onion, garlic, chives, and crocus, are acaulescent. The aboveground growths you see in these plants are specialized leaves called scapes. Dandelions, carrots, pineapple, cilantro, lettuce, spinach, and California poppies are also acaulescent. In each case, leaves emerge from a ground level base. Some species of cycad, primrose, oxalis (Oxalis triangularis), and palm (Attalea cuatrecasana) are also acaulescent. Why should you care?
Knowing that a plant is or is not acaulescent will not change the way you care for it or harvest it. What this information will help you do is to identify those mystery plants that keep turning up in your garden or foodscape. Knowing words such as acaulescent makes you sound pretty smart, too! |
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