Flowers come in many shapes and sizes. When a flower cluster has a flat or dome-shaped profile, it is said to be corymb [kor-im].
Corymb comes to us from the Greek word (korumbos) for ‘cluster’. The only reason this information is important, besides helping you win more often in word games, is that it can help you to identify plants of mysterious parentage. So, let’s find out more about corymbs and flower clusters. [And don’t let all the new words scare you off.]
Umbels and corymbs
First, we need to differentiate between umbels and corymbs. Umbels are flower clusters that look like umbrellas. The tiny stems, called pedicels, all emerge from a central stalk. Carrot, dill, and parsley flowers are all umbels.
If a flower cluster has many branches, instead of a single point of contact, it is called a panicle. [But don’t panic! You can do this!]
Flower stems are called peduncles. As soon as the tiny stems of a flower cluster begin to emerge, that main stem changes its name to rachis [ray-kiss]. Each individual stalk within a flower cluster is called the pedicel. Each pedicel holds a floret. Pedicels can be arranged in pairs (parallel), or they can take turns (alternate).
Types of corymbs
Corymbs may be flat-topped or convex. This is because the tiny stems, or pedicles, get progressively longer as they move away from the center. If the pedicels of a corymb all emerge from the central rachis, it is said to be racemose. If there are several layers of branching rachis, it is called cymose.
Cymose corymbs are said to be determinate. Determinate inflorescences have a flower on the top that halts further growth. This top (apical) flower is the oldest one in the bunch. Younger flowers develop below this primary flower. Forget-me-nots, jasmine, and figs are all cymose.
Racemose corymbs, or racemes, are said to be indeterminate. Indeterminate inflorescences are those with the oldest florets at the base and newer growth at the top. They just keep on growing. Cherries and other stone fruits all have racemose corymbs. Snapdragons and yerba maté are also racemes.
The next time you look at a flower cluster, take a moment to see if it is built like an umbrella (umbel), if its branches are all connected to a central stem (raceme), or if there is a complex system of branches (cymose). This can help you make better use of the many plant identification tools available online.
Accessory fruits are not designer handbags or the latest fad. In the word of botany, accessory fruits are more familiar that you might expect.
What is fruit?
Fruit is the tissue that surrounds the seeds of angiosperms (flowering plants). Fruit tissue is made from the ovary. Except when it isn’t. In some cases, a fruit develops from both the ovary and nearby tissue, found outside of the carpel. These neighborly tissues can be either the perianth, the flower whorls, or the hypanthium, the flower base. When this occurs, the part we eat is called an accessory fruit.
Popular accessory fruits
Using our botanical definition of an accessory fruit, we learn that pineapples are accessory fruits because the fruit is made from the ovary plus tissue from the pistils and sepals. We also learn that strawberries are accessory fruits. [The seeds you see on a strawberry fruit are actually achenes, a type of dried fruit. Each achene develops from a single pistil.] Other popular accessory fruits include apples, figs, mulberries, and pears. And those delicious cashew nuts? Those are the seeds of the cashew apple, another accessory fruit.
Now you know.
The truth about nuts may surprise you.
While you probably already know that peanuts are not nuts (they’re legumes), many of the other foods you have come to know as nuts are not true nuts at all. Let’s begin by learning the botanical definition of nuts.
True nuts are hard-shelled, inedible pods that hold both the fruit and the seed of a plant. These pods do not open of their own accord, which means they are indehiscent. The pod, or shell, of a nut is made from the ovary wall, which hardens over time. Hazelnuts, chestnuts, and acorns are true nuts. So are kola nuts, which gives “cola” soft drinks their signature flavor.
[Did you know that small nuts are called ‘nutlets”? To me, that sounds like the perfect name for a little chihuahua.]
So, when is a nut not a nut?
A nut is not a nut when it is a fruit seed. Fruit seeds can be angiosperm, drupe, or gymnosperm seeds:
These not-nut nuts are commonly referred to as culinary nuts.
[Did you know that cashews are the seeds of an accessory fruit, which means they share characteristics with strawberries and poison ivy. Isn’t botany amazing?]
Of course, you can call any of these delicious morsels "nuts" whenever you want to. True nut or culinary nut, many of these yummy snacks find their way into our gardens and foodscapes. Which ones are you growing?
Plants do not chow down on rocks like they were burgers and fries. Instead, their menu reads more like the Periodic Table. Plants absorb water from the soil. Minerals are in that water. Those minerals are plant food. Plants also produce their own food using the sun’s energy to create sugar.
There are 16 chemical elements critical to plant health. Depending on how much is needed, they are labeled as micronutrients (tiny amounts) or macronutrients (large amounts). Macronutrients are further divided between primary and secondary nutrients. Primary nutrients are the NPK of fertilizer bags. Plants use nitrogen, phosphorus, and potassium more than any other plant food, which is why they are the ones most often needing replacement. They are the rice and beans of a plant’s diet. Secondary nutrients, calcium, magnesium, and sulfur, rarely need to be supplemented, but they are very important to plant health. Micronutrients include boron, copper, iron, chloride, manganese, molybdenum, and zinc. [These used to be called trace elements.]
If you count up all those nutrients, you will only find 13. That is because plants also have non-mineral nutrients. These non-mineral nutrients are hydrogen, oxygen, and carbon. All of these nutrients work together to provide your plants with the energy and materials needed to grow. Some of those nutrients are mobile, while others are immobile.
Highly mobile nutrients go where they are needed within a plant. Nitrogen, potassium, phosphorus, magnesium, chloride, and molybdenum are all mobile plant nutrients. All the other nutrients are considered immobile because they stay where they were initially placed. Problems with mobile nutrients tend to appear in older leaves, while problems with immobile nutrients are seen in new growth. This is important to know because it can help you narrow down deficiencies and toxicities.
What is in your soil?
Before we take a closer look at each of these important factors to plant health, let me remind you that you cannot know what nutrients are in your soil without a soil test from a reputable lab. I wish those colorful plastic tubes from the store could do the job accurately, but they can’t. Not yet, anyway. Contact a local soil test lab and find out what you are working with. Not knowing the facts can lead to toxic levels of these nutrients, which can backfire. Just because your plants are not thriving does not mean they need to be fed. All too often, plant problems are caused by inhospitable soil conditions, unhealthy roots, irrigation problems, pests, or disease.
Also, different plants have different nutrient needs. Simply dumping a box of 10-10-10 around the garden isn’t a good idea and it’s a waste of money. Those chemicals can pollute groundwater and damage beneficial soil microorganisms. It can also make plants grow faster than they can maintain over the long haul, leaving them weak and vulnerable later in life. [For a hysterical read about the effects of too much fertilizer, check out Don Mitchell’s Moving/Living/Growing Up Country series.]
So, let’s see what each of these nutrients do for your plants:
Not enough of a plant nutrient, or too much, can cause problems. The tricky part comes in when the balance of nutrients is out of whack.
A man named Mulder created a chart that shows us the interactions between plant nutrients. Synergistic elements help each other to be absorbed by plants. Antagonistic elements get in each other’s way.
Using the chart above, you can see that proper levels of potassium help plants absorb iron and manganese, but too much potassium interferes with a plant’s ability to absorb boron, calcium, magnesium, nitrogen, and phosphorus. This interference can take the form of competition for space on water molecules, or it can alter soil pH, making some nutrients unavailable.
Plant food and soil pH
Soil pH ranges from 0 to 14, with lower numbers indicating acidity and higher numbers indicating alkalinity. Using the chart below, you can see that more nutrients are available, and there is greater microbe activity, when soil pH is between 6.0 and 7.0. Most plants can survive in soil pH from 5.2 to 7.8, but the narrower range allows plants to thrive. This is because the minerals use as food are ions. Ions are atoms and molecules that have a positive or negative charge. These cations and anions, respectively, attach themselves to water molecules and are pulled into the plant by root hairs. The wrong soil pH can cut your plants off from a bounty of nutrients.
Soil is given a cation exchange capacity rating to describe its ability to hold nutrients. [Did you know that root hairs knock cations (unbalanced atoms or molecules) loose with a hydrogen canon? Stay tuned for more on that!]
How to feed your plants
Personally, I prefer feeding my plants with composted yard and kitchen scraps and chicken bedding. Not only does this mix have excellent nutrients, it also improves soil structure. If you decide fertilizer really is necessary: READ THE BAG. Seriously. Federal law requires that important information is printed on the container and for good reason. Follow directions carefully and wash your hands when you’re done. Technically, there is no chemical difference between nitrogen from compost and nitrogen formulated in a lab. Nitrogen is nitrogen. The difference lies in everything else. What are the fillers? What else is in the compost that plants need? Honestly, there’s a lot we don’t yet understand about how living things interact. I prefer to err on the natural side, just in case.
Finally, keep in mind that a 10-pound bag of fertilizer does not contain 10-pounds of plant food. The numbers next to the letters tell you the percentage of total weight. This means that a 10-pound bag of 10-20-10 fertilizer contains 1 pound nitrogen, 2 pounds phosphorus, 1 pound potassium, and 6 pounds of filler. Yes, filler. If all your plants need is nitrogen, blood meal is a far better choice.
What are your plants hungry for?
Plant prickles are skin spikes.
Unlike thorns, which are modified shoots, and spines, made from modified leaves, prickles are spiked skin extensions.
Because prickles are made out of epidermis and cortex tissue, they can occur anywhere on a plant. This is also what differentiates them from the hairs (trichomes) growing on your squash plant leaves. Trichomes only contain epidermis tissue, whereas prickles contain both epidermis and cortex.
The purpose of prickles
The most obvious purpose of prickles is to make plants less palatable to herbivores. Chewing on a stem covered with prickles can’t be very appealing. In extreme cases, such as the silk floss tree, the entire trunk is covered with massive prickles. I suppose that’s the level of protection needed in rural South America.
While prickles are generally meant to keep herbivores away, most species specific pollinators have learned to maneuver around the prickles without too much trouble. Prickles can also provide limited amounts of shade or insulation from temperature extremes.
A rose by any other pokey bit
Everyone calls the sharp bits on rose stems thorns, but they are actually prickles. One easy way to tell if a protuberance is a prickle, thorn, or spine, is by how easy it is to remove. Spines and thorns contain vascular bundles, but prickles do not.
This is why it is so easy to flick a rose thorn from its stem, while trying the same trick on your orange tree won’t work. Orange tree thorns have added strength from the phloem and xylem, carrying water and nutrients into the pointy protuberance. Thorns do not have that type of attachment, so they are easier to remove.
So, now you know the difference between thorns and prickles.
Pulses are the grain seeds of plants in the legume family.
Legumes are a great high protein, high fiber food that tends to be pretty easy to grow. Popular legumes include beans, peas, lentils, chickpeas, cowpeas, and fava beans, just to name a few. Soybeans, carob, peanuts, tamarind, and alfalfa are also legumes, but not all legumes produce pulses.
Legume fruits, or pulses, are simple dry fruits that are low in fat. They develop from a single carpel and are normally dehiscent, which means they unzip along one edge. These fruits are often called pods, but that isn’t exactly inaccurate. Pulses are only one type of pod. A radish silique and a vanilla capsule are also pods. While peanuts and soybeans are both legumes, they both have a high fat content, they are not considered pulses.
No green pulses
If you harvest peas or beans while they are green, they are not called pulses. They are simply vegetable crops (even though they are fruits). The same is true for legumes harvested specifically for their oil. This is a rule put out by the United Nations’ Food and Agriculture Organization (FAO).
Differences between pulses and cereal grains
Cereal grains, such as rice, wheat, barley, corn, and sorghum certainly deserve garden space for their seed crops, they are not the same thing as pulses. Pulses may seem like just another bunch of seeds, but there are fundamental differences that make them stand alone:
The only true pulses are the seeds from dry beans, dry peas, chickpeas, and lentils. These plants provide one of the best bangs for your gardening buck, providing excellent nutrition and soil health improvement.
Hesperidium is the name given to certain types of fruits.
Hesperidia are berries with a tough, leathery skin that tends to be bitter.
If you cut a hesperidium open, you will see separate compartments, called carpels. Within these carpels, you will see hundreds of tiny, fluid-filled vessels that are made out of specialized hair cells. These vessels are called vesicles.
If you haven’t already guessed, all citrus fruits are that special type of berry, known as hesperidia.
Bud scar may sound like a great punk band name, but knowing how to recognize this tiny bit of plant anatomy can come in handy.
At the tip of most twigs is an area of meristem tissue. This plant tissue can turn into several different types of plant cells. When the tissue grows upward, to continue the trunk of a tree, or a branch stem, it is called apical meristem, or a terminal bud. In this sense, terminal does not mean lying on its death bed. Rather, it refers to the bud at the end of the branch.
As these terminal buds burst forth with new growth, the protective scale normally falls away, leaving a bud scar. Bud scars look like rings around stems and branches of trees and other woody plants. Bud scars are from the terminal bud on a stem. These marks are different from leaf scars. Leaf scars occur at the point of attachment for a leaf, after the leaf has fallen off. Just above a leaf scar, there is usually a lateral bud that can grow into a twig or flower.
Ultimately, the growth of the tree or branch will grow over these scars, but that can take a long time. Until then, you can use the number of bud scars to determine the age of a branch, since each terminal bud indicates one year’s growth.
As a child, I would eat around the center core of my carrots, leaving the darker, sweeter core for last. I didn’t know it then, but that inner core is called the stele.
Vascular plants have both root and stem steles, but they didn't start out that way. Primitive steles were nothing more than a strand of xylem, surrounded by phloem. [Remember, water and minerals ‘rise up the xylem’ from the roots, and manufactures sugars ‘flow down the phloem’ from the leaves. In case you forgot.]
More modern steles may consist of vascular tissue, pith, and pericycle. Pith is the spongy material seen in the center of stems, and the pericycle is a thin layer of tissue between the xylem and the endodermis. There are two major types of stele: protostele and siphonostele.
Protostele describes the more primitive stele, which consists of a strand of xylem, surrounded by phloem. Protosteles may or may not have an endodermis that controls the flow of water. There are three different types of protostele:
Siphonosteles are a little more complex than protosteles. Siphonosteles may have gaps in their vascular tissue in places where leaves are born. These spaces are called leaf gaps. You can think of these leaf gaps as sections cut from a hula hoop and pulled a little apart, making room for leaf tissue to grow through. Siphonosteles also contain pith. If the xylem is found only outside of the pith, it is called ectophloic. If the xylem can be found both within and outside of the pith, it is called amphiphloic. Members of the nightshade family, such as tomatoes and peppers, are amphiphloic. There are three types of amphiphloic steles:
Diseases of the stele include phytophthora root rot, verticillium wilt, black root rot, and crown rot. In each case, prolonged exposure to wet soil creates the conditions needed for pathogens to infect your plants. Maintaining good drainage and soil structure can help prevent these diseases.
So, why would you care what sort of stele your plants have? Besides sounding really smart, being able to look up information about what’s inside a plant stem can help you identify unknown plants.
What's inside your stems?
Every rose has its thorns, right? Well, no. They don’t.
Roses do not have thorns. Roses have prickles. Citrus trees have thorns.
Thorns, prickles, and other spiky bits
Thorns are a type of spinose structure made out of a modified leaf, stem, root, or bud. Many people use the terms bristles, prickles, spines, and thorns interchangeably. Botanically, these terms mean very different things:
So, where bristles are stiff hairs and prickles are hard, spiked skin (neither of which contain plant veins), spines, being modified leaves, and thorns, modified stems, do contain plant veins.
Plants use thorns as a mechanical defense against herbivores (and gardeners). Cacti are far less likely to be eaten when they are covered with hard thorns. And the pollinators who specialize in pollinating these particular types of plants seem to be unaffected by the presence of thorns. In some cases, thorns are also used to shade certain plant varieties, or to provide a layer of insulation.
Home, sweet thorn
Some thorns are hollow. These tiny chambers are called domatia. Plants, such as certain acacia species, produce domatium to provide shelter for beneficial arthropods (insects, spiders, and crustaceans). Similar to galls, which are produced by the resident, rather than the landlord, domatium are the plant’s side of a mutually beneficial relationship, most commonly with ants or mites. Occasionally, thrips may also move into these tiny apartments, but they are generally unhelpful to the plant. The plants that create these thorny thresholds are called myrmecophytes.
While I do not expect any of you to stop calling rose prickles thorns, why not impress your friends with your new-found knowledge?
Wax is made by honey bees to build the comb used to store honey and to protect larvae.
Did you know that plants also make wax?
Nearly all vascular plants manufacture wax. This wax is used as part of the cuticle, or outer layer of the epidermis, of leaves, stems, and even some fruits.
Having a waxy outer layer reduces evaporation, making it easier for plants to hang on to the water they need. It also reduces the chance of abrasion, when plant parts rub against each other. Finally, wax makes it more difficult for pests to attack.
Wax is actually a class of fatty compounds that are insoluble in water and tend to be relatively soft at room temperature. When honey bees are between 12 and 20 days old, they develop a special gland on their belly that converts the sugars in honey into waxy flakes. The flakes are collected by other bees and chewed up before being used to make new comb. [I thought you’d want to know about that.] Plants, however, have neither the organ nor the chewing ability. Instead, plants synthesize wax out of hydrocarbons, made up of fatty acids and long chain alcohols, along with aromatics, ketones, and other chemicals. The chemical make up of a plant’s wax varies by species and geographic location.
Plant wax candles
Carnauba wax, of shiny car and confectionary fame, is a wax made by the Brazilian palm Copernicia prunifera. A lighter colored substitute, ouricury wax, comes from the Brazilian feather palm Syagrus coronata. Several species of native bayberry (Myrica cerifera), also known as wax myrtle, and the succulent stems of candelilla (Euphorbia antisyphilitica), produce so much wax that they were used by Native Americans to make candles. In the case of bayberry, the berries are boiled until the wax separates from the plant material. After it hardens, it is removed from the soup. These candles are still made today, due to the pleasant smell as they burn. Candelilla plants are now endangered and collecting them is forbidden. Other plant waxes include castor wax, rice bran wax, and tallow tree wax.
The next time you look at a leaf or stem, take a closer look and see if wax is part of that plant’s defense system.
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 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.
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 diaheliotropism protects plants from overheating and dehydrating.
How do your plants move during the day?
What bottle of wine would be complete without its cork? The same is true of most trees.
Everyone knows that trees and woody shrubs are made of wood, surrounded by bark. But there’s a lot more going on in those outer layers than meets the eye.
The bark you see protecting the living wood of a tree is made up of dead plant cells. This layer is called the rhytidome. The reason these cells are dead is because the cork layer cuts them off from the tree’s resources.
Components of bark
Bark is made up of three basic layers. The inner layer, or phloem, is a living part of a tree’s vascular system. Manufactured sugars ‘flow’ down the phloem to feed the rest of the plant. The middle tissue, or cortex, is made up of porous tissue that stores and transports carbohydrates, tannins, resins, and latex. The outermost layer of bark is called its periderm.
The periderm is also made up of three layers: the cork, cork cambium, and phelloderm. Cork (phellem) is produced by a specialized layer of cambium tissue, known as the cork cambium, or phellogen. This cork cambium layer is only one cell thick and the cells divide in parallel (or periclinally) toward the outside of the tree. In some trees, the cork cambium layer also produces cells towards the inside of the tree. These inner cells are the phelloderm layer.
Function of cork
Cork keeps wine safe from the elements because it is impermeable to gases and water. Because of the cork, your wine stays where it is and (as long as the cork remains intact) will only grow better with time. The cork of a tree also blocks air and water. Cork is able to keep trees and wine safe from the elements, along with insects, bacteria, and fungal disease because it contains suberin. Surberin is a waxy material that creates a protective barrier. This barrier also blocks water and gas exchanges between the outermost layers of the tree killing the epidermis, cortex, and secondary phloem. This is the bark you see.
Trees and shrubs also use cork to cut off an unwanted body part (leaf, diseased twigs, mature fruit) from the rest of the plant. This is called abscission.
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.
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.
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.
Plants cannot be green without magnesium, but too much magnesium in the soil can turn plants yellow. How can this be?
Magnesium is essential for plant health. Magnesium stabilizes cell membranes, making plants better able to withstand drought and sunburn. Magnesium is found in enzymes that plants use to metabolize carbohydrates. Most important, magnesium is contained in the chlorophyll molecules that convert the sun’s energy into food. This process, the Calvin Cycle, is what makes photosynthesis possible. Clearly, magnesium is important to plant health. But too much magnesium can interfere with the absorption of other plant nutrients.
Plants use 13 dissolved minerals as food. There are three primary macronutrients (nitrogen, potassium, and phosphorus) and three secondary macronutrients (calcium, sulfur, and magnesium). Plants use large amounts of these macronutrients to grow, thrive, and produce. Seven other nutrients, used in smaller amounts, are called micronutrients. Fertilizers claim to provide all the food your plants need, but it’s not that simple. [Is it ever?]
The chemical interplay, taking place in the soil, that allows plants to absorb nutrients, is a delicate balancing act. Too much, or not enough, of one nutrient can create a domino effect that causes starvation for plants that are surrounded by a banquet of nutrients.
What is magnesium?
Magnesium is an elemental metal. Pure magnesium (Mg) is too stable of a molecule for plants to absorb. The less stable, cation form of magnesium (Mg2+) is a dissolved salt that plants use for food. To be able to attract and hold those positively charged molecules, plants also need negatively charged molecules (anions), such as nitrogen, phosphorus, and sulfur. The ability of soil to perform this balancing act is called its Cation Exchange Capacity (CEC). Without a soil test from a reputable, local lab, you cannot know your soil’s CEC or nutrient levels.
For example: My first soil test found magnesium levels of 798 parts per million (ppm). The ideal range is 50 to 120ppm. Clearly, before I moved in, someone was applying an awful lot of fertilizer. The problem they were probably trying to correct was not insufficient nutrients, but a nutrient imbalance. Without a soil test from a local, reputable lab, you simply do not have enough information.
Base saturation and magnesium
Soil test results also include base saturation figures for potassium, calcium, and magnesium. Base saturation is the percentage of available connections being used. [Think of it as how many grocery bags you can carry in from your car.] The optimal range for magnesium base saturation is 10 to 30%. This means that soil particles, because of their electrical charge, will ideally hold on to 10 to 30% of the magnesium in the soil. It takes the right absorption percentage and the right volume of magnesium in the soil for plants to be healthy.
My soil’s magnesium base saturation was 32%. That sounds close enough to the 10 to 30% optimal range, right? The problem is, with seven times the amount of magnesium needed in the soil, my plants were getting 32% of too much.
Too much magnesium in the soil makes it difficult for plants to absorb calcium and other anion nutrients, which can lead to blossom end rot, bronzing, and many other problems. This is a common problem in areas with alkaline soil. The opposite is true in areas with acidic soil. Insufficient magnesium symptoms look very much like potassium toxicity symptoms: older leaves, at the bottom of the plant, start turning brown, between and alongside the leaf veins, working upward through the plant. Magnesium deficiencies in stone fruits often start out as slightly brown areas along leaf edges (margins) that expand inward, causing cracking, necrosis, and leaf loss. Magnesium deficiency in California is extremely rare.
Stabilizing magnesium levels
Reaching and maintaining ideal mineral levels in soil for healthy plant growth is both science and art - mostly science. To start, get a soil test from a local, reputable lab. Unfortunately, over-the-counter soil tests are not yet accurate enough to be useful. Once you have your results, you can take these other factors into consideration:
Finally, schedule regular soil tests for your garden and landscape. Look at these tests as an annual physical for the living skin of your property. The information in these tests will help you make informed decisions about the magnesium in your soil.
If you pick a dandelion, you will see a viscous, milky white goo come out of the stem. That goo is latex. Exposed to the air, latex coagulates, creating a protective barrier. Plants use latex as a defense against insect feeding. [Slugs will eat leaves drained of latex, but not before.] We use latex in very different ways.
Latex gloves, latex paint, and cosmetic sponges all get their start from latex. So do chewing gum, balloons, adhesives, and opium. The latex collected from the rubber tree is where we get, you guessed it, rubber. [Most latex paint, such as is used in whitewashing, is actually a synthetic latex.] It is estimated that 10% of all flowering plants, angiosperms, contain latex.
What is latex?
Latex is an emulsion made up of of proteins, fats, starches, sugars, oils, resins, alkaloids, tannins, and gums. Emulsions are mixtures of two or more liquids that generally do not mix - think salad dressing. Homogenized milk and mayonnaise are also emulsions. Normally, latex is thick and white, but it can also be yellow, clear, orange, red, or watery.
How is latex different from sap, or resin?
Sap is the combined water, sugars, and plant nutrients that move through a plant’s vascular bundles to feed and water the plant. Resins, like latex, are protective substances that ooze from injury sites. Unlike latex, which coagulates and dries, resins create a hard, crystalline barrier.
How do plants make latex?
Latex is produced and transported in a separate system called the laticiferous system. There are two methods of latex formation and movement. Articulated laticifers consist of rows of plant cells found in the meristem tissue of stems and roots. The walls of these cells dissolve, creating tubes, called latex vessels. This method is common to poppies, fig trees, mulberries, rubber trees, and members of the sunflower family. Non-articulated laticifers, such as milkweed and spurge, develop a branching network of latex-producing cells throughout the plant. In some cases, the entire network is made from a single cell.
Plants that produce latex
There are over 20,000 species of plant that produce latex, occurring in over 40 plant families. Some of the more commonly known latex-producing families include:
Some mushroom, conifer, and fern species also produce latex as a defense mechanism.
Allergic reactions to latex
Because latex contains defensive chemicals, it can be an irritant. Prolonged exposure can lead to an allergic response, as can multiple surgeries, or spina bifida. Individuals with a latex allergy are at risk for anaphylactic shock and should avoid contact. Some forms of latex can cause blistering of the skin, or blindness, while other plants produce a latex with reduced amounts of the allergen. These forms are being researched as an alternative.
As you work in the garden, note which plants exude latex when damaged. And monitor your skin for reactions to this liquid plant defense.
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 an area 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.
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 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.
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!
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!
When you look at a flower, you probably notice the petals first. Bright colors and brilliant arrangements attract people and pollinators alike. All of those petals together are called the flower’s corolla, or inner perianth. At the base of that corolla, you will sometimes see a green cup shape made up of lobes. The lobes together are called the calyx, or outer perianth. Each lobe, individually, is called a sepal.
Sepals encase a bud before the flower blooms, providing protection. Usually, after the flower blooms, the plant has no use for the sepal and it is allowed to whither. Some flowers retain their sepals, using the cup-like structure for added support for the flower. In some cases, such as oyster plants, the sepals are quite large and they protect the nyctinastic flower during the afternoon and through the night. Tomatillos and groundcherries, however, put their sepals to work as papery outer coverings for their precious fruit. These protective bladders help keep birds and insect pests away.
Like flower petals, sepals are modified leaves. While often smaller than the petals, sepals can be longer and larger. Sepals can look like teeth, ridges, or scales, especially on plants in the grain family, or they can look like leaves or petals. Normally green, they can also be very colorful and may look like petals. When the petals and sepals are too difficult to tell apart, they are called tepals. Flowers with tepals are called petaloid. Tulips and aloe plants are petaloid.
Some sepals are attached or fused to each other (gamosepalous), while others are separate from one another (ploysepalous). When the sepals are fused toward the base, as in the case of legumes and pomegranates, they form a calyx tube. In the rose and myrtle plant families, this structure is called the hypanthium.
Sepal count and plant classification
The number of sepals present can help with plant identification. The number of sepals is called its merosity. Eudicots generally have a merosity of four or five, while monocots and palaeodicots have a merosity of three. If you see a flower with 4 or 8 sepals, you will know that it is a eudicot. If it has 3, 6, or 9 sepals, it is either a monocot or a palaeodicot. If is has 15 sepals, well, you’re on your own.
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. Th 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, 3 or 4 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!
You can grow a surprising amount of food in your own yard. Ask me how!