Garden Word of the Day
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Sometimes plants grow in ways you might not expect.
Instead of a nice round stem, you see a flattened ribbon shape. Rather than a regular flower, you get undulating folds. In flowers, it is called cockscomb or cresting. Wherever it happens, it is called fasciation.
Fasciation is a relatively rare physiological disorder that can create some beautiful mutations. It can occur anywhere on a plant, but stems and flowers are the most commonly seen examples.
How does fasciation occur?
In normal plant development, growing tips (apical meristems) focus all their resources on a single point, creating straight or cylindrical stems and flowers. Fasciation elongates the apical meristem, creating a ribbon-like growth. The Latin fascia means band.
In some cases, these distortions can create unique bends, twists, odd angles, or unusual clusters of growth that look like a witch's broom. Flowers and leaves growing on these distorted stems may be smaller, more abundant, or have other unique characteristics.
One rare form of fasciation, ring fasciation, has a ring-shaped growing point that creates hollow tubes.
What causes fasciation?
Plant hormone imbalances, genetic mutations, environmental conditions, or disease can all result in fasciation. It can also occur for no apparent reason. Possible environmental factors include chemical overspray or exposure, mite or other insect infestation, and certain fungi. Exposure to cold and frost can also cause fasciation. Fasciation is not contagious unless caused by bacteria.
Plants affected by fasciation
Milkweed, nasturtiums, geraniums, dandelions, and ferns may all exhibit fasciation. It also occurs in fruits and vegetables, such as asparagus and broccoli.
Some plants are prized and propagated simply because of their fasciation.
Galls are like warts or tumors in the plant world.
Not really. Galls are neither warts nor tumors, but that’s how many of them appear. The word gall comes from the Latin galla, for oak-apple. Oak apples are not fruits. They are a plant’s reaction to the presence of a foreign substance.
The study of plant galls is called cecidology [see-SID-ology]. Most commonly associated with baseball-sized knobs seen on oak trees, galls come in all sizes and can occur on many different plants.
Galls are swellings that occur in response to invasion. That invasion may be in the form of bacteria, fungi, insect larvae, eriophyid mites, nematodes, other pests, and even other plants. Mistletoe is one example of a gall-forming plant. Unlike fungal cankers, which involve plant tissue death, galls, fungal or otherwise, are cases of extra tissue growth.
Galls are nearly always woody knobs that may occur anywhere on a plant. Galls may be simple, with a single chamber (unilocular), or highly complex, with multiple pockets (plurilocular). Galls can also look like a sphere, a saucer, pineapples, pinecones, pouches, pods, or fantastic, tiny red spikes. It just depends on the host plant and the cause of the gall.
Where they occur and how they look inside can tell you a lot about what caused them.
If you cut a gall open, you will see distinctly arranged vascular tissues, depending on the cause of the gall, and an enlarged cambium layer. These distortions interfere with the flow of water and nutrients, leading to wilting and stunting. Or, you may see a large, open area, perfect for use as a larval nursery, with no noticeable impact on the host plant.
Insect, mite, and nematode galls
When insects invade a plant, they build galls. These galls can act as food or shelter for insects. They are not the same as the plant-produced domatia (tiny apartments) found in some thorns for beneficial insects. Insects inject chemicals (pseudo plant hormones) into host plants, triggering gall formation. Often, eggs are laid in these galls, providing developing larvae with food and protection. Gall wasps, sawflies, gall flies, scale insects, some aphid species, weevils, psyllids, and gall midges can all cause insect galls, but it is nearly always gall wasps or gall midges.
Nematodes are microscopic round soil worms that can cause small galls on roots. Root knot nematodes are one such pest. These galls are made up entirely of plant tissue, unlike fungal and bacterial galls, which incorporate fungal or bacterial tissues, respectively. Insect galls may also house interlopers, technically called inquilines.
When a fungus infects a plant, it grows alongside plant cells, creating swollen areas that can develop into galls. Several varieties of rust can cause galls to form. When these galls form on conifers, as in the case of cedar apple rust, they look like glutinous fingers called telial horns.
Fungal galls on other types of leaves tend to look more spherical.
Bacterial and viral galls
Bacterial and viral galls develop because the bacteria or virus reprograms plant cells into producing more bacteria, viruses, or other supportive cells. Galls at or just below the soil level are nearly always crown gall. Crown gall is a bacterial disease that can occur on blackberries, sunflowers, grapes, and roses, along with almond, apple, apricot, cherry, and pear trees.
Galls on roots may mean clubroot, a disease caused by parasites known as Phytomyxea. On the other hand, root galls may also indicate the presence of beneficial, nitrogen fixing Rhizobium bacteria. Galls have long been used in leather tanning, to make ink, and as astringents. Most galls contain high levels of tannic acid and resin. There are even a few edible galls, corn smut being the most notable. Sometimes, what looks like a gall is herbicide overspray.
New and undifferentiated plant cells are most vulnerable to gall formation. Spring is a good time to monitor plants for signs of galls. Once gall development begins, the tissues have been reprogrammed and cannot return to normal.
In a word, you can’t. Insect and mite galls rarely harm plants, and you can’t control these pests completely, anyway. Once they are inside the plant, there is nothing you can spray or apply that will reach them. Anyway, the gall is already in place.
Fungal and bacterial galls may be prevented or reduced with fungicide treatments if you can time it perfectly. Or not.
If you are galled by galls, remove them with a sharp knife. Otherwise, recognize that galls are just another amazing aspect of playing with plants.
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?
Bronzing your baby's shoes is one thing; bronzing in the garden indicates a problem.
What is bronzing?
Bronzing refers to how some leaves or fruit turn purplish or bronze-colored due to mineral imbalances, pest feeding, chemicals, environmental conditions, or disease. Bronzed leaves are often smaller, and damaged areas cannot perform photosynthesis. Bronzing damage may look similar to sunburn damage, except that sunburned leaves tend to turn gray rather than bronze. Bronzed fruit has a dry, rough texture.
Too much or too little of certain minerals can cause bronzing. Regularly adding organic material to your garden soil helps minimize mineral imbalances. But it’s still a good idea to know what to look for when scouting your foodscape:
Chlorine deficiency – More likely in sandy soils, symptoms include bronzing, stunting, necrosis, chlorosis, and wilting.
Copper deficiency – Copper deficiencies are rare. When they occur, they make trees look more like shrubs than trees. Bronzing, shoot, twig and needle dieback, and witches’ broom are common symptoms.
Iron toxicity – Iron toxicity often appears as bronzing and reddish spots. These symptoms are from iron oxidizing the chlorophyll used in photosynthesis. In areas with heavy clay soil, insufficient iron is more likely.
[Did you know that rice farmers rate their plant varieties using leaf bronzing scores (LBS)? They rank rice varieties according to their ability to tolerate excessive iron in the soil.]
Manganese deficiency – Manganese is an immobile nutrient, so deficiencies are seen in younger leaves first. Manganese deficiencies look very similar to iron (Fe), magnesium (Mg), and nitrogen (N) deficiencies, with interveinal chlorosis and bronzing. Brown specks may also be visible.
Sodium toxicity – Too much sodium can cause severe chlorosis, bronzing, and leaf drop. Stunting and other water stress symptoms are also common.
Zinc deficiency – Rare in most areas, zinc deficiencies appear as twig dieback (necrosis), yellowing (chlorosis), and leaf bronzing, often caused by too much phosphorus in the soil. Zinc deficiencies are more common in container plants.
As pests feed, leaf and fruit bronzing may occur. Most of these pests are sap-suckers:
Damage can occur when herbicides, pesticides, and fungicides are incorrectly applied. Also, the wind can carry herbicides and other chemicals from neighboring gardens and yards that may cause leaf bronzing. Bronzing, necrosis, interveinal chlorosis, desiccation, and distorted growth may indicate chemical misuse or overspray.
Air pollution often causes high ozone (O3) levels in the atmosphere. Ozone, combined with high temperatures and bright sunlight, can cause purple-brown discoloration, or bronzing, on the upper surface of leaves. Bean plants are especially vulnerable to air pollution.
Many plant diseases include bronzing as a symptom. These include spotted tomato wilt (carried by thrips), phomopsis stem canker in sunflowers, alfalfa mosaic, cotton root rot, and blueberry bronze leaf curl.
Use bronzing as a clue when you walk through your garden. The brownish or purplish discoloration of bronzing is a clear sign that something is amiss.
Thee’s a lot more to wind than meets the eye.
You may not see it, but gentle breezes and wailing typhoons are both laden with insect pheromones, fungal spores, viruses, and bacteria. Gentle breezes help plants get stronger, while gale force winds can rip trees from the ground.
Seedling development is mostly decided by sunlight, moisture, and temperature, but wind is important, too. Being blown around stimulates the stem into growing stronger. This is called thigmomorphogenesis. Plants grown in greenhouses, without any wind, actually get gently knocked around by a machine that helps prevent the plants from becoming too tall and spindly. While most pollen is too sticky to be affected by wind, wind is the primary mechanism for pollination of corn plants.
Note: My eye doctor told me that pollen is too sticky to wipe or rub off your eye lashes, so don’t try. You can damage your cornea. Believe me. It takes soap and water.
Wind dries plants out. Plants exposed to a lot of wind are generally going to need more water. Wind can also speed erosion, which is why ground covers and mulch are such good ideas. During heavy winds, you may want to move containerized plants next to a fence or wall, to prevent breakage. Tall plants can be protected against wind damage with stakes, tree supports, and tomato cages. Wind damage can be in the form of branches flailing around and tearing holes in leaves, and causing branches to rub together. [See pruning.] Wind damage provides pathogens with a way in. And hot summer winds can lead to blossom drop and fruit set failure.
Strong winds can rip heavily laden branches or overly large limbs from a tree, leaving jagged wounds. You can help these trees recover quickly by cutting the wound to make it a flat surface, close to the trunk, but not cutting into the branch collar. You do not need to paint the wound. Instead, allow the tree to protect itself. It will grow a callus over the area. You may, later on, need to provide the callus with sunburn protection.
Diseases on the breezes
Disease causing pathogens are usually microscopic. As such, they can catch a free ride on every breeze that comes through. [I wonder if that would make it a case of phoresy…] In any case, there are several diseases that can arrive in your garden on the wind. Gray mold (Botrytis cinerea) is always blowing around in the wind, which is why rotting fruit gets that gray fuzz so quickly. It’s everywhere. Mummy berry spores blow into your garden on the wind. So, do chemical oversprays. The chances of ringspot on Brussels sprouts skyrockets after a windy day, and citrus blast often occurs right after periods of wind-driven rain. You can reduce the chance of citrus blast by providing citrus trees with some measure of wind protection.
Wind protection can take many forms. It may be a fence, a hedge, or a row cover. You can protect plants by installing plants next to your house, or close to a large tree. You can protect smaller plants against cold winter winds with a portable cold frame. When spring comes around, wind can really mess up a plant trying to get established in a new location (ecesis). Wind is one of the main reasons for taking the time to harden off plants started in protected areas. And when you start planting those tiny seeds, such as lettuce, you can often lose most of your crop to the wind. The wind simply blows the seeds away. [You may want to check your neighbor’s yard for all that lettuce and endive you planted last year…] And all those delicate seedlings that do emerge can be protected from wind by covering them with a plastic gallon jug (cloche) with the bottom cut out. Just be sure to bury the edges or weigh down the jug enough to prevent it from blowing away, too!
Plants as windbreaks
Just as some plants and most seedlings need protection from the wind, other plants can provide that protection. Pineapple guava, mature blueberry bushes, and many fruit and nut trees can be used as a wind break.
Finally, I wanted to share this with you. While researching wind and its impact on plants, I learned that there are three types of wind:
1. On Earth, it can be the “bulk movement of air” across the planet’s surface.
2. In outer space, charged particles or gases moving around is called solar wind.
3. When our beloved planet outgases light chemical elements, it is called wind.
I never knew that our planet outgassed anything. So, now you know. Our planets farts into outer space.
Evil hides beneath the calyx, yet you hold it close.
Sorry, I couldn't resist. The calyx is part of a flower. The reason I say ‘evil hides beneath’ is because that is where many fruit rotting fungi hang out.
Calyx as flower part
Calyx is another word for sepal. Sepals are the green petals at the base of a flower that are modified leaves. The calyx is also the green leafy area at the top of a strawberry fruit. Sometimes, the calyx is the same color as its flower. In most cases, once a plant is done with the flower, the calyx is discarded. Tomatillo plants retain the calyx as a thorny protection. In other cases, the calyx begins to grow in earnest after the flower is fertilized, creating a protective bladder-like enclosure. The sepals of Hibiscus sabdariffa turn into an edible accessory fruit.
Calyx as hiding place
Many fungi, such as botrytis cinema, love to hide under the calyx, waiting for a splash of rain or irrigation water to start breeding gray mold and feeding on your berries and other garden produce. Sometimes the calyx falls victim to the very pathogens it protects, along with the fruit, as in the case of stem-end rot. In some cases, such as calyx blight, only the calyx becomes infected and the fruit remains fine.
How many different types of calyx are in your garden?
Epinasty refers to how leaves and stems turn downward when their tops grow faster than their bottoms.
While many plants move to follow the sun's path each day (phototropism), sometimes plant movements are more random. These are called nastic movements. Epinasty is a nastic movement.
Herbicide overspray can cause severe epinasty. This crazy growth occurs because many popular herbicides are synthetic auxins (plant hormones) designed to drive a plant to grow itself to death.
[If your tomato plants are exhibiting downward curling leaves, it may be that the soil needs more time to dry out between waterings.]
When roots experience flooding, they generate an amino acid that I cannot pronounce, but botanists call ACC. ACC is the ethylene precursor. ACC moves up the xylem, where it converts to ethylene gas. This ethylene stimulates roots to create hollow tubes that connect to adventitious roots. These structures draw oxygen into the plant.
Other signs of ethylene exposure include chlorosis, thickening stems, petal loss, and deformed or aborted flowers. Epinasty from ethylene gas is common among plants grown in greenhouses with poorly maintained propane or natural gas heaters.
Transplanting young seedlings is a rite of spring for many gardeners. Learn how to transplant your seedlings safely and easily to help them thrive.
Benefits of seed starts
Some plants, such as lettuce, have very tiny seeds that need light to germinate. Planting these directly in the ground often leads to losses due to wind dispersal or rotting under too much soil. Starting these plants in containers makes it easy to monitor them closely and keep the soil moist until the seeds sprout. As seedlings grow, they can become root bound, which means the roots start wrapping around the inner wall of the container. Many store-bought plants are root bound. Before this happens, you can up-pot or transplant those seedlings. Up-potting means moving a seedling from a small container to a slightly larger container. Transplanting means moving the plant to where it will live out its life.
When NOT to transplant
Plants that are fruiting, flowering, infested, or infected should generally not be transplanted. New transplants need to be able to focus on building a strong root system. Also, just as some people are more sensitive than others, some plants do not take kindly to being transplanted. The following plants should be sown directly into the ground whenever possible:
How to transplant seedlings
For many vegetable crops, you can transplant seedlings with the first leaves (cotyledons) below the soil line. Very often, these meristem tissues will transform into root tissues, adding nutrients and vitality to your plants. Once your seedlings are a couple of inches tall, you should prepare their new home, making sure that the soil is loose. The Bay Area’s heavy clay can form an impenetrable barrier to new roots if it is left smooth from a trowel or shovel. Be sure to rough up the edges of the planting hole. Then, follow these steps to successfully transplant your seedlings:
Caring for new transplants
New transplants should be treated gently for a few days. To help a young seedling thrive in its new environment (ecesis), be sure to:
Be sure to use plant markers when transplanting. This will help you recall where everything is!
Holiday Plant Care
Poinsettias, Amaryllis, and miniature Christmas trees make delightful gifts during the holiday season, but they need special care to last.
Two plants couldn’t be more different than poinsettias and miniature pine trees, and their care is equally diverse. In each case, if these plants are simply set on a countertop and watered occasionally, they will probably never make it to the end of January. Amaryllis plants are often watered to death. Being bulbs, your holiday Amaryllis can last for several years, given the proper care.
Understanding what these popular holiday gifts need to stay healthy can transform them from short-lived hostess tokens to durable members of your garden, landscape, or home interior.
Poinsettias (Euphorbia pulcherrima) are fascinating plants. The bright red blooms we see are bracts or modified leaves. The plant itself is a tree that can reach 13 feet in height! The flowers of poinsettia plants are tiny structures hidden away in pseudo flowers called cyathia. Native to Mexico, poinsettia plants need 12 hours of darkness for at least five days in a row to turn from green to red, in a process called photoperiodism. The slightest exposure to sunlight, street lights, headlights, or table lamps will interfere with this process. Poinsettias need strong morning sunlight and afternoon shade to be healthy. They can be grown outdoors, in warmer regions, as long as they are protected from frost.
Commercially grown poinsettias are infected with a phytoplasma (bacteria) that causes the plant to produce abundant lateral buds, which make the plant grow in a more bushy structure. Poinsettias left on their own have a more open, spindly growth. Poinsettias are susceptible to certain fungal and bacterial diseases, including leaf spot, stem rot, crown gall, anthracnose, blight, black rot, dieback, gray mold, powdery mildew, rust, scab, mosaic, and root-knot nematodes. These tendencies indicate the importance of allowing plants to dry out between waterings and providing good drainage. The University of Vermont Extension provides an excellent way to remember how to care for your poinsettias:
As a member of the spurge family, poinsettias contain latex, which can be an irritant. Contrary to popular belief, poinsettias are not poisonous.
In early fall, as the leaves begin to turn brown, cut the leaves back to 2 inches from the bulb and remove the bulb from the soil. Clean the bulb and place it in the crisper drawer of your refrigerator for 6 weeks. Just be sure there are no apples nearby, as they will sterilize your amaryllis bulb! After 6 weeks in the cooler, bulbs should be returned to the soil about 8 weeks before you would like fresh blooms. This cycle can continue for several years.
Most holiday plants receive too much water, not enough sunlight, and too much heat to make it through the holiday season. Understanding what these popular holiday gifts need to stay healthy can transform them from short-lived hostess tokens to durable members of the garden, landscape, or home interior.
If you slice into a stalk of celery, you will be able to see vascular bundles that carry water, nutrients and hormones throughout the plant. These vascular bundles, or veins, are made up of the xylem and phloem.
The xylem mostly carries water. Xylem is Greek for wood, so an easy way to remember the word meaning is to think “water wood”. The xylem also carries some mineral salts, but that is mostly the job of the phloem. Generally, the xylem is found closer to the center of a stem, while the phloem is closer to the outer edge.
The most interesting thing about the xylem is that it pulls water upward from the ground, against gravity. If you’ve ever picked up a bucket full of water, you know this isn’t always easy. There is some debate about how this actually occurs, but most botanists agree that it has a lot to do with surface tension.
Water molecules like to stick together. As a plant breaths, evapotranspiration occurs, reducing the amount of water in the leaves and stem. The water in the ground in then pulled upward by the water in the above ground portion of the plant. The structure of the xylem helps support the water molecules as they are drawn up.
Xylem vessels are actually made up of elongated cells that are dead. Weird, right? These cells are arranged end to end, with little openings between each cell. There are secondary xylem cells that contain lignin. Lignin is found in cell walls and it is what holds plants upright.
Diseases of the xylem include Fusarium wilt, root rot, damping off, and tomato spotted wilt.
Children's activity: This is crazy easy and the kids seem to really enjoy it. Simply take several celery stalks and place them in separate cups or glasses. To each cup, add some water and a few drops of a specific food coloring. As the stalks pull the water up, they bring the dye too, and the color changes can be striking. (It works faster if you trim the base of each stalk to create fresh openings for the vascular tissue.)
No, it's not a new brand of mouthwash.
Chlorosis is the plant equivalent of a human gasping for air. It is the word used to describe the yellowing or bleaching of leaves frequently caused by insufficient sunlight. Or, it might be too much water or disease. Or it might be pest feeding. Or a nutrient imbalance.
Plants suffering from chlorosis are unable to produce chlorophyll. Since plants need chlorophyll to help them convert sunlight into energy, it’s a significant problem that warrants a closer look without delay.
If you notice chlorosis on any of your plants, consider these possible causes:
When I first bought my home, I sent soil samples to the University of Massachusetts Extension lab. [I think over-the-counter soil tests are a waste of money.] For the price of a bag of fertilizer, I learned exactly what was (and wasn't) in my soil.
My soil test results told me that my soil had a superabundance of every nutrient known to humanity except iron. Since plants use iron to process nearly every other nutrient, the previous owner kept adding more fertilizer whenever her plants started yellowing. As a result, the soil had too many nutrients, interfering with the delicate chemical dance between microorganisms, plant roots, water, and nutrients.
I sprayed my plants with liquid iron and applied ammonium sulfate. Over a few years, I was able to bring the excessive nutrient levels down a bit (which is harder than you might expect) and iron levels up. As a result, chlorosis was less common, my plants were healthier, and I saved money on fertilizer that I didn't need.
As soon as you correct the problem causing chlorosis, your plant's little energy factory will kick right in. Everything should start greening up pretty quickly.
You can grow a surprising amount of food in your own yard. Ask me how!
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