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.]
Traveling in Germany a few years ago, I was a little confused by grids of 20-foot poles pointing skyward. They looked alien, like a giant, bristling growth. That was before I learned about hops.
Hops are flowers from the Humulus lupulus plant and they love to grow up!
Hops in beer
I do not know how to make beer, so my knowledge in this area is limited. [Brewers, feel free to add better information in the Comments!] I do know that hops have been used in beer-making since the 9th century. Before that, other flowers and bitter herbs were used, including dandelion, marigold, horehound, and burdock root, in a mash called gruit. One of the main reason brewers switched to using hops was because there was a tax on gruit, but no tax on hops. Of course, that situation was only temporary. Hops are said to have an antibacterial effect, as well as providing a bitterness that balances malt’s sweetness. It is the unfertilized female flowers that are used in beer-making. The acids in beer have sedative properties, with or without alcohol.
The flavor and aroma of hops flowers is largely the result of where they are grown. While there are many different hops cultivars, the plants can be [overly] simplified into three different types: American, British, and Continental European. American hops are robust, heavy producers with long sidearms. They tolerate a wider range of soil pH and soil structures. American hops are generally planted 4 feet apart in rows that are 14 feet apart. Common American varieties include Willamette, Chinook, Brewers Gold, and Zeus. British and Continental European varieties are genetically different from the American varieties. They have smaller, finer root systems and are less tolerant of soil variations. These varieties have shorter sidearms and can be grown 3 feet apart in 12-foot rows. This allows for more plant density on the same acreage. British varieties prefer more alkaline soil (pH 6.5 or higher) and can tolerate heavier soils. Common British varieties include Viking, Fuggie, and Challenger. Continental European varieties, such as Magnum, Glacier, and Pearle, prefer more acidic soil (pH 5.5 to 6.2). One subset of the European hops, referred to as noble hops, are less bitter, with a stronger aroma than others. These hops are used to make Pilsners and other mild beers.
Hops plant structure
Hops flowers are green, soft-petalled seed cones, also known as strobiles. Hops plants are dioecious, which means the plants are either male or female. To prevent male pollen from fertilizing the female flowers, plants are propagated vegetatively. When hops plants are grown from seed, the males are culled as soon as they are seen, similar to other flower bud crops. The hops vine is called a bine. As the bine wraps around a support, side branches, called sidearms, emerge. At the end of the growing season, everything aboveground dies back. In spring, the roots put out new bines and the whole process begins again.
How hops grow
Hops plants are fast growing, perennial climbers. That’s what all those poles and strings were - hopfields or hop yards. Hops grow from rhizomes that are placed in ‘hills’ or mounds that are 6 to 12 inches high. This helps with drainage. The rhizomes are placed 4 inches below the soil surface. Commercially produced hops are generally started in pots, in March. Then they grow in greenhouses until July. Plants are placed 7 to 8 feet apart in a grid formation that matches a series of poles that support strings used by the hops plants to climb toward the sun. In these commercial fields, air flow is critical to disease and pest management, so the bottom 3 feet of foliage is removed. If you are growing just a few plants for yourself, you don’t need to do that.
Hops prefer very specific conditions, requiring moist, temperate regions with plenty of boron in the soil. Most of the world’s hops production occurs along the 48th parallel north, which includes Germany, China, and Poland. Hops grow well in the same conditions preferred by potatoes, making Idaho, eastern Washington, and parts of California and Oregon good hops growing country. One acre can produce 2,000 to 3,000 pounds of mature hops flowers, on average.
You do not need to install 20-foot telephone-style poles in your yard to grow hops. One neighbor of mine simply attached strings from a fence to the roof of his house. Each spring, the bines emerge and lovely green flowers appear in late summer, shading the sunny side of his house! You can also grow hops using a tee-pee of bamboo poles, just to see what it’s like.
Pests and diseases of hops
Powdery mildew and downy mildews can be particularly troublesome. Mites and weeds become more problematic as interior sunlight and air flow increase.
Hops are toxic to dogs, so do not grow hops in areas frequented by Fido. You can, however, eat the young bines the same way you would eat asparagus.
One way plants store food and reproduce is with a structure called a corm.
Many corms produce two different types of roots. Familiar fibrous roots anchor the plant in the soil and absorb water and nutrients. Contractile roots pull corms deeper into the soil, away from animals and extreme temperatures. Contractile roots stop pulling the plant downward as conditions above improve.
Caring for corms
When a plant grows from a corm, it draws moisture and carbohydrates from that underground structure. By the time the plant reaches its mature size, much of those resources have been used up and must be replenished. Use these tips to help your corms stay healthy:
Do you any corms in your garden?
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:
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.
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.
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.
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.
Cardoons (Cynara cardunculus) are edible thistles from the sunflower family.
Eaten the same way as celery, or cooked into stews and soups, cardoons are a maintenance-free perennial. The familiar, grocery store variety of artichoke is a type of cardoon, but there are differences.
Native to the dry climate of Morocco, cardoons are unfazed by drought, making them an easy choice in California and other Mediterranean climates. Also known as artichoke thistles, cardoons produce magnificent pinkish-purple spiked flowers from April through July, but it is the stems that are eaten.
Wild cardoons are sturdy herbaceous perennials that grow 3 to 5 feet tall, with deeply lobed, greenish-grey leaves that can be spiny, hairy, or downy (a condition called tomentose). The fleshy taproot is very good at finding water. And pollinators love the big, showy flowers!
Cardoons are grown for two different crops, using different cultivars. The familiar globe artichoke (Cynara cardunculus var. scolymus) is grown for its large edible flower buds. The plant referred to as ‘cardoon’ (C. cardunculus var. altilis) is grown, instead, for its edible leaf stems. Since the wild ancestor to cardoons featured painful spines on those stems, spineless cultivars have been developed. Our domesticated artichokes and cardoons are so closely related that they can cross-pollinate, so they should be grown a fair distance from one another.
How cardoons grow
Cardoons need a long, cool growing season, making them an excellent winter crop in the Bay Area. Seeds are started late fall to mid-winter and they transplant easily. These plants grow slowly, at first, but don’t let them fool you. Cardoons can get quite large, averaging 3 feet in all directions. Plants need full sunlight, moderate amounts of water, and good drainage. Watering regularly improves the flavor of cardoon stems. They are frost sensitive, so some protection may be needed in the form of mounded straw or dry leaves around the base of the plant during winter. The plants often die back to ground level after flowering, but they will come back, year after year, adding structure and color in winter, and a spectacular show in spring and early summer.
Only the tender, inner stalks are eaten. These are harvested before the plant goes to flower. Much like celery, these stalks are wrapped in fabric, paper, or straw during the 30 days of growth. This etiolation, or bleaching, keeps the stems white and tender. Traditionally, the stalks were buried under a mound of soil as the plant grew, but that just sounds like too much work. The stalks are then peeled and treated with a little lemon juice, to prevent browning. Simmer for 30 minutes or so and add to any number of Moroccan, African, Greek, Italian, or Persian dishes. In addition, cardoon seeds contain a high quality oil, similar to sunflower oil and safflower oil.
Cardoon pests and diseases
Like its close cousin, the artichoke, cardoons are vulnerable to feeding by slugs and snails, and the artichoke plume moth. They are also susceptible to the viral disease artichoke curly dwarf. Other than that, they are relatively indestructible.
An invasive weed
Cardoons are so hardy, and they self-seed so readily, that they are categorized as a Most Invasive Wildland Pest Plant by the Invasive Species Compendium. What this means to you, as a home gardener, is that it is very important that mature flowers are deadheaded before seeds can spread. This will protect the environment and prevent your yard from filling up with pokey thistle plants. Cardoons grow and spread so readily that some researchers are studying them as a source of biofuel and bioplastics materials.
Invasive weed or delicious vegetable, cardoons have been part of the human diet since ancient times, only falling out of public favor over the last 100 years.
As easy as it is to grow, perhaps it is time for a cardoon in your foodscape!
Cambium is the layer of plant tissue responsible for the secondary growth of roots and stems.
When a plant first starts to grow, all it knows is up and down. But, once it’s basic systems are in place, the plant can start filling out. This secondary growth is why tree trunks, branches, and some roots get thicker as they grow. This secondary growth is all because of cambium.
What is cambium?
Cambium is a thin layer of living tissue, found between the xylem and phloem of vascular plants, that manufactures the new cells used in secondary growth. Cambium cells are parallel to each other and they encircle the stem or trunk. The cambium layers produce secondary xylem and phloem cells.
Where is the cambium layer?
There are actually two different layers of cambium tissue and each is found where it will do the most good. But, before we explore the different types of cambium, let’s review a little plant anatomy. Working our way in from the outside, a tree trunk is made up of various layers:
Types of cambium
There are two different types of cambium. They are cork cambium and vascular cambium.
Cork cambium produces new bark on its outer edge and it has a layer of cells containing chlorophyll on its inner surface. If you scrape the outer bark off of a twig, you can usually see a green area under the bark. This is the cork cambium layer. Potato skins are another example of cork cambium tissue. If you are ever lost in the woods and hungry, you can eat the cambium layer of most pines, slippery elm, black birch, yellow birch, red spruce, black spruce, balsam fir, and tamarack trees. [I have no idea how it tastes. At that point, you probably won’t care.]
Vascular cambium is where most of the width of dicots and gymnosperms is produced. [Most monocots lack secondary growth.] Vascular cambium is found between the phloem and the xylem. Vascular cambium produces xylem tissue on its inner surface and phloem tissue on the outer surface. You can see the vascular cambium in herbaceous plants as beads on a necklace when a cross-section is taken.
Cambium through the seasons
In spring, when water is more abundant, the ring produced by the vascular cambium is usually wide and light colored, while the portion of that ring produced later in the summer is usually darker and thinner. These two rings together represent one year of growth. The cambium layer is relatively inactive during cold periods, which is why plants don’t do as much growing in winter. Many gardeners take advantage of this fact when grafting new scions onto existing trees and other plants. It is the cambium layers of both plants that must connect for a graft to be successful.
Damage to the cambium
If the cambium layer is killed by fire, freezing, pests, or disease, the plant will die. Many animal pests are attracted to the moisture found in the cambium layer. Gophers, ground squirrels, voles, deer, horses, and rabbits will gnaw through the outer bark, especially during severe drought. This activity can girdle a tree, killing it. Deliberate girdling (removal of the outer bark around the circumference of a tree) is used to increase fruit yield, size, and quality, but care must be taken to not damage the cambium layer. Tree supports, left on for too long or tied too tightly can also damage the cambium layer, killing the tree.
Many insect pests will burrow their way into the cambium layer, using it as food, breeding grounds, and protection. Very often, these insects can kill a mature tree. They include bark beetles, American plum, shot hole, Pacific flathead and other borers. If that weren’t enough, freezing temperatures and fungal cankers, such as phytophthora, armillaria, crown gall, and crown rot, can also kill the cambium layer.
Sapsuckers are a type of woodpecker that drill a series of holes in the bark and cambium of trees to get at the sap and the insects attracted to the sap.
Who (or what) is attacking your plants' cambium layers?
“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.
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:
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.
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)
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.
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.
Diamondback moths are common pests of cole crops.
Cole crops include broccoli, Brussels sprouts, cabbage, cauliflower, and Napa cabbage. That’s where I saw the damage. My Napa cabbage was growing very nicely, enjoying our cool winter weather, but the leaves looked more like Swiss cheese. That’s because diamondback caterpillars prefer older leaves, so the first sign of infestation you will see is a bunch of holes in the larger leaves. They also feed on flower buds and flower stems.
Diamondback moth lifecycle
Adult diamondback moths (Plutella xylostella) lay their eggs on the underside of leaves and they are very difficult to see. When the eggs hatch, tiny caterpillars burrow their way into the crown for safety. When a diamondback moth caterpillar is disturbed, it will jump ship, rappelling away from danger using a thin silken thread to swing to safety. After feeding for a couple of weeks, diamondback moth caterpillars spin a loose cocoon on nearby leaves or stems, where they pupate.
Diamondback moth control
Personally, I have caught a few diamondback moths on good old fashioned fly paper strips. That isn’t a very effective control method however. Maintaining biodiversity in your garden is one way to attract the ichneumonid wasp, a predator of diamondback moth caterpillars. Spraying Bacillus thuringiensis and spinosad are effective organic control methods.
Sunny yellow flowers, toothed leaves, and a seed head that simply begs to be blown are all characteristic of the weed commonly known as dandelion.
The word dandelion, which means lion’s tooth, actually refers to several different plants in the sunflower family. Native to Europe and Asia, dandelions have been following humanity across the globe, taking advantage of soil disturbed by agriculture, fires, and construction. This makes them a ruderal species. Ruderal species are the first plants to colonize disturbed land.
Bane of lawns everywhere, the common dandelion (Taraxacum officinale) was brought to North America in the 1600s to be used as both food and medicine. The species name officinale refers to an early English word meaning medicinal.
Cousin to lettuce and chicory, dandelions are easy to recognize, with their low-growing (basal) rosette of toothed leaves and bright yellow or orange composite flowers. Composite flowers are actually made up of several florets, clustered together. Dandelion florets reflect ultraviolet light, which attracts many beneficial insects, looking for nectar and pollen. Surprisingly, dandelions do not need to be pollinated to set seed. Instead, seeds are produced asexually, in a process called apomixis. As a result, all offspring are identical to the parent plant. Besides the floral stem, dandelions are acaulescent, which means they appear to not have any structural stems.
Dandelion flowers open each morning and then close each night, in a behavior called nyctinasty. Each plant can produce up to ten floral stems. The cuplike structure seen at the base of each dandelion floret is called a calyculus. Once the flower has matured, it will begin to dry out. After the dried petals and stamens fall off, specialized leaves, called bracts, curve backwards, exposing the seed ball. Each stem produces a single seed ball. These seed balls are commonly called blowballs or clocks. The seeds we see are actually a special type of fruit, called a cypsela. The feathery bristles that act like a sail are called pappi (pappus, singular). The hollow flower stem contains a bitter latex used to defend against herbivores.
Latex is used to make rubber. While most of the latex used to make rubber today comes from the rubber tree (Hevea brasiliensis), you can make your own rubber from dandelion latex! You can make an elastic band simply by coating your finger with dandelion latex, allowing it to dry, and then rolling the latex off your finger. Voilà! You can also make a bouncing ball or waterproof fabric out of dandelion latex. [Did you know that a man named Charles Macintosh figured out how to smear latex between two pieces of fabric to make waterproof fabric? That’s why raincoats are often called macintoshes!] When dandelion latex dries, it stays sticky until it cures. Curing latex involves applying heat and sulfur. The curing process removes the stickiness. Dandelion rubber is stiff in cold temperatures and supple when it is warm. Only Russian dandelions make a latex that is strong enough to be used commercially. [I just learned that one company is researching the use of Russian dandelion latex to make automobile tires!]
Dandelions as food
All parts of the dandelion plant are edible, but you may want to harvest the newest leaves to avoid some of the plant’s bitterness. Eaten the same way as spinach, dandelion greens are packed with good nutrition, including high levels of vitamins A, B, C, and D, according to the University of Maryland Medical Center. Dandelions also contain a lot of iron, calcium, potassium, and zinc. Young dandelion roots can be peeled and eaten. They are said to taste like turnips, but I haven’t tried them yet. The roots can also be roasted and used as a coffee substitute. The flowers are also edible. They can be sautéed in oil with a little garlic and they can be used to make dandelion wine.
Dandelions as medicine
Traditionally, dandelion has been used to treat infections, digestive problems, as a mild laxative, and to stimulate the appetite. Dandelion leaf tea was said to “purify the blood” and the milky latex was used as both mosquito repellent and wart remover, though I couldn’t find any scientific proof to back up any of these claims. According to WebMD, no research has demonstrated any verifiable medicinal use of dandelion, though it does contain chemicals that decrease swelling and increase urine production.
These herbaceous perennials have taproots that are strong enough to counteract compacted soil. Hell, they can break through concrete! While dandelion roots are typically only 6 to 18 inches deep, some specimens go 10 to 15 feet deep! Dandelion plants can live for up to 10 years and reach 20 inches in diameter.
I used to try to eliminate dandelions from my lawn, despite my love for their bright yellow flowers and the irresistible seed heads. I finally decided to try putting the plants to work for me in my heavy clay soil. While mulching and growing green manures and cover crops has significantly reduced soil compaction on my property, I have a theory about dandelion taproots. It goes something like this: Since dandelion taproots are strong enough to break asphalt, I allow them to grow, regularly removing the greens (for salads and as a treat for my chickens), before flowers emerge. My theory is that the dandelion taproots will dig down into my compacted soil, bringing microorganisms with them, to create healthier soil. Even if it doesn’t work, I still get pretty flowers and edible greens. Maybe I’ll even try making dandelion wine, one of these days. If my theory is wrong and I end up with a severe problem with dandelions and other, similarly growing weeds, I make have to resort to other control measures.
If you really must get rid of the dandelions in your lawn, it will take consistent effort on your part. As you already know, those seeds can blow in on the wind from miles away. This battle never ends. While herbicides will certainly kill individual dandelions, those same chemicals can be toxic to other living things, such as us, and our pets. Maintaining a healthy lawn and removing plants as soon as they are seen is the best control method. Cutting off young plants at ground level, a practice called grubbing, is effective only if you are diligent. Crabgrass preemergent herbicides advertised as effective against dandelions do not prevent seeds from germinating.
Love ‘em or hate ‘em, dandelions have been around for 30 million years, and they are here to stay.
You may as well make the most out of these common weeds.
Aphids, or plant lice, are nearly always a problem, here in San Jose, California. This is particularly true when it comes to cabbage aphids.
Cabbage aphids (Brevicoryne brassicae) can wipe out a cabbage crop before it ever gets started. Native to Europe, this pest of cole crops is now found throughout the United States.
Vulnerable young cabbages
Cabbage aphids feed on the youngest, most tender parts of new cabbage, broccoli, Brussels sprouts, kale, and cauliflower. These pests love to feed on the innermost parts of cabbage and Brussels sprouts heads. Large colonies can stunt or even kill young plants. Heavy aphid feeding causes leaves to curl up, providing the pests with even more protection.
Cabbage aphid description
Like other aphids, cabbage aphids are soft-bodied sap-sucking pests that can reproduce at an alarming rate. While cabbage aphids are actually grayish-green, they look powdery blue to grayish-white because of a waxy covering. They are not difficult to see, since they live in dense colonies that can cover stems, new leaves, and entire plants practically overnight. Here in California, these pests produce live offspring year round.
What’s really amazing about these pests is that they produce an enzyme, in their head and throat muscles, that gets combined with defensive chemicals (glucosinolates) from their host plants, to create a "violent chemical reaction" that releases mustard oil. This “walking mustard oil bomb” defense is particularly effective against ladybug larva.
Controlling cabbage aphids
Prevention is key to cabbage aphid control. My cauliflower plants, which had been protected under row covers, were left untouched, while my cabbages and broccoli were hit hard. Once aphids are seen, you can often use a strong spray from the garden hose to dislodge them. If that doesn’t work, insecticidal soaps can provide some control. Since soap may be phytotoxic, especially on cabbage and Brussels sprouts, it is a good idea to apply them on a foggy day. Also, remove any weeds in the mustard family from the area. Cabbage aphids can hide out in the mustard and then return to your garden. Pesticides can be used, as a last ditch effort, but aphids are developing resistance to these chemicals and that can be a dangerous spiral.
Another problem with using pesticides against cabbage aphids is that those same chemicals also kill beneficial, predator insects, such as lady beetles, parasitic wasps, and the syrphid fly (hoverflies). These helpful insects are natural predators of caterpillars, imported cabbageworms, diamondback moths, loopers, and armyworms, which can cause other problems for your cole crops.
Monitor your plants every couple of days and be on the lookout for cabbage aphids!
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.
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.
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?
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!
Living in a drought prone area, I think I’d much prefer Madagascar’s endangered Bottle Tree, or baobab (Adansonia grandidieri). When it rains, the bottle tree absorbs as much water as it can, up to 30,000 gallons! These trees can grow to nearly 100 feet tall.
Finally, one small African flower, the Parachute Plant (Ceropegia linearis), attracts pollinator insects and then pulls its petals together, temporarily trapping the insect. As the insect walks around, seeking an exit, pollination occurs.
There is probably no limit to the number of ways a plant can adapt.
What are the plants in your garden doing to adapt? And how can you help them?
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.
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
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:
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.
Saddle up, garden buckaroos!
Today we are going to learn about spurs - fruit spurs, that is!
Fruit spurs are where fruit grows. Sometimes. Sometimes fruit grows on twig tips. And some fruit trees use a mix of the two. This is called their cropping behavior. Knowing which method your tree uses and being able to tell the difference between a leaf bud and fruit spur will help you make better pruning choices when training fruit trees. This is best done while trees are dormant because there are no leaves to block your view.
Leaf buds v. fruit buds
Fruit trees generate two different types of buds: fruit buds and growth buds. Growth buds can become leaves or twigs, while fruit buds hold flowers. On some trees, a cluster of leaves may end up surrounding a fruit bud, but those tend to come later in the season. Growth buds are slender and pointed. They are smaller than fruit buds, as well. Fruit buds tend to be round and fat. In some cases, fruit buds are covered with fuzzy scales. And, many times, they grow on fruit spurs.
What are fruit spurs?
Fruit spurs are stubby little twigs that grow only 1 to 6 inches long. Sometimes they grow singly along a branch, as with peaches, and sometimes they grow in clusters, as on apple trees. Depending on the type of tree, the fruit spurs may produce fruit the first year, the second year, or for several years in succession. Some fruit spurs are productive for 10 years or more!
How to use this chart
The chart above tells you the cropping behavior of many common fruit and nut trees. Using it, you can see that fig trees produce fruit laterally, on long, first year wood. This means that regular annual pruning of various branch lengths will increase fruit production. Apple trees must be treated very differently. Apple fruit buds rarely occur on long shoots, laterally (along its sides) or at the tips. Nearly all apple fruit buds are found at the end of fruit spurs. This means that you would want to avoid pruning those spurs until they have stopped producing fruit altogether. [There are apple varieties that produce fruit at stem tips, called tip-bearers, and others that use a mix of the two, called partial tip-bearers, which is why it’s a good idea to find out as much information as you can about each of your fruit trees.]
The easiest way to tell if your fruit tree produces fruit buds on spurs is to go outside and look.
Branch collars are one way trees seal off injuries.
Picture, in your mind’s eye, a young tree growing towards the sun. Every so often, a branch starts to emerge from the side of the thickening trunk. This is what they do. Now, picture a side branch that grows in a way or a place that requires its removal. Where do you make the cut? Tree pruning is an excellent way to maintain good tree health and increase production. Doing it incorrectly, however, can kill your tree - and it's all about the branch collar.
What is the branch collar?
The branch collar, or callus roll, is the raised area that surrounds the base of every branch. This where tree growth changes from trunk to branch. You may also see a wrinkled area where a branch meets the trunk. This is called the branch bark ridge. But the branch collar is where trees produce the protective callus. Damage the branch collar and infection is sure to occur.
If you want to learn more about branch collars at the cellular level, check out Horticultural Science’s pdf Tree Branch Attachment to Trunks and Branch Pruning. In it, Alex L. Shigo describes how branch tissues develop, bringing the xylem and phloem along for the ride, to feed the new branch. Fascinating stuff!
How trees heal
When a limb is cut, the tree seals off the area with a dry covering called a callus. The callus is generated in the branch collar and slowly works its way toward the center of the cut. If the branch collar is damaged, the tree cannot seal the area off properly. Often, this is how moisture enters a tree, leading to rot and decay and, potentially, the death of a tree.
Tree pruning - the Wrong Way
Research has shown us that there are many common misbeliefs about tree trimming:
In each of the above practices, more harm is being done than good, and all because of the branch collar.
Making a better cut
Looking at each of the Bad Ideas listed above, let’s see what makes them detrimental to your tree’s health:
Instead of doing it the Wrong Way, you can put the branch collar to work for you and train your tree to grow better and stronger.
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.
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.
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!
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.
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!
The letters V, F, and N on a seed packet or plant label refer to certain types of disease resistance and pest tolerance.
All of us work to make our plants healthier. At the end of a growing season, many of us save seeds from the very best fruits and plants for next year. [If you’ve never done this before, I urge you to give it a try. I’ll write about seed saving tomorrow.] By saving and planting seeds from the best plants each year, we are choosing specimens that are better suited to our microclimate and personal tastes.
Building better plants
When we save and plant seeds from specific plants, we are cultivating certain characteristics. A more intensive method of building better plants is to purposefully pollinate one plant with the pollen of another. Taken to the far end of this spectrum, we have plants that are genetically modified in the lab. [I used to be bothered by this, until I learned that plants have been doing it to each other for a very long time. See Dodder.] These manipulations are often used to encourage certain characteristics such as color, flavor, days to maturity, disease resistance, or pest tolerance.
Disease resistance and pest tolerance
Some plants are susceptible to certain diseases, while others are not. The same is true for pest infestations. In both cases, you can generally use the disease triangle to reduce the impact pests and diseases have on your garden. The disease triangle consists of the environment, the plant, and the problem. Change one of those three and the problem can be reduced or eliminated. Installing plants that are already resistant to some of your garden’s more common problems can reduce your workload and keep your plants healthier. That’s where V, F, and N come in.
V is for verticillium wilt
The V tells you that a particular plant is resistant to verticillium wilt. Verticillium wilt is a soil-borne fungus that attacks tomatoes, peppers, berries, snapdragon, eggplant, potatoes, and over 300 other garden edibles. Plants infected with verticillium wilt exhibit chlorosis, wilting, and leaf drop as the fungi breed, blocking the flow of water and nutrients through vascular tissue. Verticillium wilt fungi can stay in the soil for several years, so infected plants should be thrown in the trash. If you have a garden patch affected by verticillium wilt, use crop rotation and plant non-host species, such as beans and other legumes, broccoli, corn, and cereal grains. Non-host species are not affected by this disease.
F is for fusarium wilt
Fusarium wilt is another soil-borne fungal disease. As these fungi (Fusarium oxysporum) reproduce, they cause bleaching, chlorosis, stunting, damping-off, and brown veins. Fusarium wilt frequently attacks peas, beans, and other legumes, tomatoes, tobacco, sweet potatoes, cucumber and other cucurbits and even banana plants. There are actually several different strains of Fusarium wilt, so you may see F, FF, or FFF, depending on which strain the plant is resistant towards. [Check with your local County Extension Office to learn which strain is in your area.]
N is for nematodes
There are good nematodes and there are bad nematodes. Bad nematodes feed on the roots of several different garden plants and fruit trees. Aboveground symptoms include afternoon wilting, chlorosis, and a general lack of vigor. To verify a nematode problem, you have to dig the plant up. Nematode feeding causes swollen areas, called galls, on the roots. Roots will also look stunted and deformed.
Seeing V, F, and N is not a guarantee. It simply tells you that a particular variety of plant is resistant. Sometimes, that little extra resistance can make all the difference.
Capers are pickled flower buds.
Used to flavor to fish, poultry, sandwiches, soups, salads, and martinis, immature buds from the caper bush have been collected, dried, brined, and then pickled for over 2500 years. This plant thrives in harsh conditions, with only a little water, making it a good choice for San Jose, California.
The caper bush
Caper bushes (Capparis spinosa), also known as Flinders Rose, are broadleaf perennial evergreens that thrive in harsh conditions, with very little water. Native to Australia and Southern Eurasia, caper bushes are now naturalized throughout many Mediterranean regions. Plants can grow 2 to 3 feet high and wide, though they tend to stay low to the ground. Round or oval edible leaves are thick and leathery. Showy white or pinkish-white flowers (2-3”) feature several pale purple stamens and a sweet fragrance.
After the flowers have attracted pollinators and fertilization has occurred, caper berries emerge. Caper berries are oblong fruits that contain many seeds. These fruits are also pickled and eaten, along with the leaves. Caper bushes have strong relationships with mycorrhizae (root fungi) that help them extract nutrients from poor soils. Capers grow well on rocky areas and in soils with higher than normal salinity.
How to grow capers
You can grow your own capers from seed. Simply place fresh seeds in rich potting soil, with good drainage, and add water. Older seeds may have entered dormancy and will need stratification (cold treatment) to germinate. Caper bushes can also be grown from stem cuttings. Stem cuttings are most successful when tender new shoots are used. Instead of producing leaves at leaf nodes placed below the soil level, they produce roots. Rooting powder (auxin) is commonly applied to encourage root growth. Caper bushes produced by cuttings are generally less drought tolerant in their early years than plants produced by seed, so water accordingly. There are poisonous varieties of caper, so be sure to get your seeds or cuttings from a reputable supplier.
Caper bushes love wet springs and hot, dry summers. They grow best in USDA Hardiness Zones 8 - 10, in full sun. While they can tolerate temperatures above 100°F, they do require frost protection. Once a caper bush is well established, the root system and soil level stump may be able to withstand limited freezing temperatures.
The smallest, youngest flower buds make the best capers, so daily harvesting is recommended during the flowering season (May through August). When they are ready to pick, caper buds will be dark, olive green, and about the size of a kernel of corn. (They shrink during pickling.) Caper bushes produce curved thorns, so be careful! One of the nicest things about growing your own capers is if you happen to miss a few buds, you end up with beautiful, fragrant flowers! It's a win-win situation!
The tangy flavor of capers is partly from the salt and vinegar used in brining, and partly from the mustard oil produced by the plant.
Did you know that it is capers that give tartar sauce its unique flavor? I didn’t either.
Note: If you are a Santa Clara County (CA) resident, caper bushes are on the Qualified Plants List for the Lawn Replacement Rebate. It’s an excellent way to get paid to replace your lawn with something more productive and environmentally friendly!
Common names are usually region specific. A plant’s scientific name, however, stays the same all over the world.
The science of names
Certain scientists, called taxonomists, love to classify things. They use a system of names that show how closely everything is related to everything else, based on shared characteristics. This all started way back in the early BC’s with Dioscorides (die-oh-score-ih-day) and Theophrastus (thee-oh-frass-tis), but Pliny the Elder’s encyclopedic Naturalis Historia (77AD) is recognized as the first attempt at classifying plants (and every other living thing known at that time). It wasn’t until 1753, when Carl Linnaeus published Species Plantarum (“The Species of Plants”) that the world had a comprehensive plant naming system. Since Latin was the language of educated Europeans at that time, it is still used today as the universal scientific language. If you see a plant name followed by an L., you will know it was classified by Linnaeus.
This sorting by shared characteristics files everything into a series of increasingly specialized categories. Here is a list, using the standard garden tomato as an example:
If you have a hard time remembering the order of these classification words, try this popular mnemonic: Dear King David came over from Great Spain. Or you can try making up your own!
Under each of these headings, there can be subcategories and super-categories, but don’t let that scare you off. The most important information is what’s on the label. The two Latin words next to a plant’s common name tell you the genus and species of that particular plant.
Genus and species
The first word is the genus, or generic name. This word is always capitalized, and either underlined or italicized. The next word, in lowercase, tells you the species, or epithet. The species is also either underlined or italicized, but it is not capitalized. The genus and species can provide basic information of growth habits and good cultural practices. Once you have a plant’s genus and species, you can get even more information from its variety or cultivar name.
When a species has a naturally occurring mutation that reproduces consistently, it is called a variety. To indicate a variety, the abbreviation var. is found after the species name. The variety name is not italicized, underlined, or capitalized. Taking the example above one step further, with a red cherry tomato, we have S. lycopersicum var. cerasiforme.
When a mutation occurs as a result of human intervention, be it through selective breeding, cultural practices, or genetic engineering, the plant is called a cultivar. Cultivars are “cultivated varieties” and you will see cv., followed by a name in single quotations to indicate the cultivar. Cultivar names are capitalized, but they are never underlined or italicized. Again, we can use the above example to see the name of my favorite yellow cherry tomato, the Sun Sugar (S. lycopersicum cv. ‘Sun Sugar’).
Scientific plant naming - then and now
In its early stages, plant taxonomy was based on obvious shared characteristics, such as whether a plant produced seeds or spores, was vascular or non-vascular, and whether it was herbaceous or woody. This method worked well enough for a time. With the advent of genetic testing, plant naming, or botanical nomenclature, has gone through some changes. This is why you may see two different Latin names for the same plant. In fact, there are currently several different classification systems vying for dominance in the world of plant names, which is why it took me so long to write this post!
The most important information to take from this post is to take the time to read those plant labels. Reputable growers are far more likely to sell you what is described on the label. Unreliable growers, not so much. Reading the label can give you a starting point when researching plants that you would like to grow in your garden or foodscape.
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!
You can grow a surprising amount of food in your own yard. Ask me how!
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