Endophytes are tiny heroes of the garden.
You rarely see them with the naked eye, but most of these tiny organisms work hard to protect our plants.
What are endophytes?
The word ‘endophyte’ literally translates as ‘in the plant’ (‘endo’ = within; ‘phyte’ = plant). Endophytes are tiny organisms that live inside plants, for at least part of their life, without causing disease. In most cases, they provide a benefit to the host. The plant returns the favor by providing the endophytes with carbon [sugar]. Endophytes can be fungal, bacterial, or viral, or they can be other plants. Endophytes are everywhere and they can occur in any place within a plant.
Some endophytes grow between plant cell walls, while others live inside plant cells, and they tend to grow at the same rate as their host. Researchers have learned that plants and their endophytes use chemical signals to communicate with each other. These communications determine which helpful chemicals and what quantities are needed by both sides of the arrangement.
The science behind endophytes is relatively new. Because of this, the definitions are still being sorted out. Some scientists include parasitic and pathogenic organisms as endophytes, while others focus on the beneficial, or mutualistic forms. That’s where I stand, for now. There are several different ways that endophytes help their host plants.
Certain endophytes help plants get the food they need. The rhizobium bacteria that helps legumes fix atmospheric nitrogen is a type of endophyte. Other endophytes break down rock phosphate within the soil, making it absorbable to plant roots. Some scientists categorize mycorrhizae, or root fungi, as a type of endophyte, while others do not. [Isn't it exciting, being on the crest of new scientific research?]
Endophytes have been shown to enhance overall plant growth. They do this by improving a plant’s tolerance of abiotic stresses, such as drought, heat stress, water stress, salinity, and poor soil. When allowed to grow naturally, these mutually beneficial arrangements make both parties stronger. Unfortunately, the use of fungicides interferes with endophyte development. Also, the use of fertilizers reduces a plant’s reliance on its resident endophytes. This is, theoretically, fine, as long as the fungicides and fertilizers continue to be supplied. As soon as these artificial treatments are withdrawn, however, host plants are left with less food and protection.
Commercial agriculture is slowly coming around to the long term benefits associated with these natural arrangements, but you can take advantage of it in your own garden right away by avoiding the use of chemical fertilizers and fungicides.
Did you know that when you inoculate legumes, you are putting endophytes to work for you in the garden? Now you know!
Leaves come in a variety of shapes. Having a firm grasp of the vocabulary associated with leaf shapes can help you to identify and talk about plants more effectively.
This is a HUGE subject, so, grab yourself a beverage and get comfortable.
When describing leaf shape, some terms refer to the entire leaf, while others refer to specific parts of the leaf, such as the edge, tip, or base. Nearly all the terms are tied closely to the Latin word forms, so you are in luck if foreign language comes easily (or if you happen to already know Latin). Personally, I am not gifted in that particular area. Luckily for all of us, Latin is a pretty reliable language, when it comes to putting pieces of words together to make new words.
Don’t let all these new words scare you off, and don't expect to be able to remember everything. You can always return to this page, or use a field guide, when describing leaf shapes or identifying unknown plants. The important thing is to become familiar with the different ways that leaves are described and categorized.
Leaf and leaflet silhouettes
Leaves are first identified by their overall shape. They can be round, triangular, oval, rectangular, or diamond-shaped:
Some leaves are shaped like a heart, kidney, fan, arrowhead, or spear:
Some leaves are shaped like a teardrop, while others look more like the silhouette of a violin, a spoon, a sickle, or a hand:
The Latin of lobes
Some leaves have protrusions, called lobes, that can be rounded (like your earlobes) or pointed. Lobes can be arranged pinnately (in pairs) or palmately (like a hand). Lobes can be gently waving lines, they can be sharp incisions, or they can fall somewhere in between. These features are usually described as relative to the midrib line. Depending on the type of lobe a leaf might have, descriptive suffixes are added:
All about the base
The way leaves attach to the rest of the plant can also provide clues for identification.
Here’s a tip
At the other end of the leaf, tip shape can also provide clues for identification. Leaf tips can be:
There is a lot of variation in leaf tips:
Take it from the edge
The edge of a leaf is called its margin. Leaf margins provide an easy classification tool, since this trait stays consistent within a species. At the most basic level, leaf margins are:
If the stem attaches to a leaf near the middle, rather than at an edge, it is peltate. [Nasturtium] If it looks as though the stem passes through the middle of the leaf, it is perfoliate. [Miners lettuce]
I will be adding more images and examples of different leaf shapes in the near future but, for right now, it has stopped raining and hailing and my garden is calling.
How many different leaf shapes can you identify in your garden?
Leaves nearly always appear singularly or paired. There’s nothing unusual about that, but the mathematics behind those arrangements may surprise you.
Take a look at a stem or flower from above. You will almost always see distinct patterns in the way the leaves and stems are organized. These patterns are called phyllotactic spirals. Very often, Fibonacci numbers and the Golden Mean (or Golden Angle) are involved. Fibonacci numbers are a big part of nature and architecture. You can get a simple explanation at the bottom of my post on garden design.
Leaves emerge along a twig or stem at points called nodes. The space between each node is called the internode. Sometimes, in the angled space between the leaf and the stem, called the leaf axil, a bud may appear. The scaly covering on buds is actually made up of modified leaves, called bud scales. Note that only leaf buds have scales; flower buds do not. Where leaves emerge, along a stem, is determined by plant hormones, called auxins.
At the most basic level, leaves emerge from a stem either individually or in pairs. Leaves that take turns up a stem, alternating from one side to the other, are called alternate. Leaves that appear in pairs are called opposite. Leaves growing close to the ground, around an upright stem, whether alternate or opposite, are called basal. Leaves arranged like an upright deck of cards are called two-ranked, or distichous [dis-ti-kus].
Alternate leaf arrangements
Most of the time, alternate leaves take turns along the length of a stem, going from side to side. In some cases, such as magnolia, alternate leaves occur on all sides of a stem, in an apparent spiral. Closer inspection will show that it is not a true spiral.
Leaf arrangement math
The fraction of a circle used to arrange leaves around a stem is very species specific. You don’t have to be a math whiz to understand this stuff, either. Let me explain:
Now look at leaf arrangement along and around a stem in the same way:
Are you with me? Hang in there! This stuff is amazing!
So, since leaves and stems are different sizes, and species have different sunlight needs, there are different fractions, or ratios of rotation, around a stem. For example, hazel leaves are arranged in 1/3 (or 120°) rotations, apricots use 2/5 rotations, sunflowers and pears use 3/8, and almonds use 5/13. This means that the leaves of an almond tree are positioned 5/13th of the pie apart. If you do the math, this works out to 38.5° between each leaf attachment, as you work your way up or down a stem.
This is where it gets really weird!
The fractions that describe leaf arrangement are almost always made with a Fibonacci number and its successor, as the numerator and denominator, respectively. Now, the number of steps taken for a leaf arrangement to work its way around a stem, before repeating the pattern, is called its gyres. A three leaf cycle of rotation has one gyre, while a five leaf cycle takes 2 gyres. The number of gyres ends up being the numerator in the Fibonacci number that describes the rotation! Holy spring bulbs, Birdman!
Whorls take this math to a whole new level
The rotation of successive whorls is nearly always one-half the angle between the leaves. For example, say you have a whorled leaf arrangement that uses three leaves. From what we calculated above, there would be 120° between each of those leaves, along the length of the stem. All the other whorls will be half that distance, or 60° apart from each other. I have no idea why.
Bottom line: whether leaves are alternate, opposite, whorled, basal, or distichous, the mathematics of leaf arrangement ends up providing each leaf with the optimal amount of sunlight.
[If you really love this stuff, check out Gray’s Botanical Textbook: Structural Botany (1879)]
Floral symmetry refers to whether or not, and how, a flower can be segmented into mirror images of itself.
Angiosperms (flowering plants) use a wide variety of structures, colors, and aromas to attract pollinators. These non-reproductive parts of a flower are called the perianth. The perianth consists of the petals (corolla) and the green cuplike structure at a flower’s base, called the sepals, or calyx.
Looking at a flower from above, if you were to cut it in half, through the perianth, the two halves might be relatively identical, identical only along one plane, or not identical at all. These different types of symmetry are called radial, bilateral, or asymmetrical, respectively.
Snowflakes and apple pies have radial symmetry. No matter how you cut them in half, both halves look the same. Flowers with radial symmetry are called ‘regular’ or actinomorphic. Actinomorphic also refers to ‘regular’ star-shaped flowers that can be divided into three or more identical sections. Each section looks the same, no matter how you rotate the flower. Even though each half may not contain a complete petal, they are still considered actinomorphic.
Most people have bilateral symmetry. This means our left and right sides look very much alike, but our fronts and backs look very different. Some flowers, such as orchids and snapdragons, are the same way. Some flowers have only one line that can be cut to create a mirror image. These flowers are classified as ‘irregular’ or zygomorphic. Zygomorphic flowers have bilateral symmetry and that line is called the sagittal plane. Lavender, olive, sage, mint, nasturtiums, basil, and rosemary flowers are zygomorphic.
Simple v. compound flowers
Flowers can be simple or compound, but don’t let the names fool you. Simple, or primitive, flowers, such as strawberries and geraniums, are actually more complicated than compound flowers. Simple flowers usually have 3 to 6 petals, sepals, stamens and pistils. Compound flowers, called inflorescences, are made up of hundreds or thousands of flowers, each with only one or two sepals and petals. To analyze compound flowers for symmetry, you would have to look at individual florets from that inflorescence. While sunflowers and dandelions may appear to exhibit radial symmetry, the actual florets may or may not be symmetrical, depending on the species.
Go take a closer look at the flowers in your garden. What sort of symmetry do you see?
The fruits and seeds that we eat are plant ovaries.
Botanically, an ovary is the enlarged base of a pistil. Pistils are the female reproductive organs of angiosperms, or flowering plants. A flower’s pistil can be made up of one or more carpels.
Parts of the ovary
Plant ovaries have walls that surround small eggs, called ovules. Ovaries often have chambers, called locules. Ovules are found inside the locule(s). Some locules contain fruit flesh, while others do not. The number of carpels also determines the internal structure of a fruit. When you cut open a melon, you will see one locule, in the center, and four distinct sections, which were formed by the carpels.
Plant ovaries and pollination
When pollen lands on the style (stalk) and stigma (sticky knob) of a flower, the pollen grain ‘germinates’, sending a pollen tube down to the ovule. This is pollination. When that pollen grain merges with the ovule, fertilization occurs. At this point, three new structures are produced: seeds, pericarp, and the plancetae.
Seeds Held within the ovary of a seed plant, are ovules. Ovules contain the female reproductive cells. Seeds are fertilized ovules. Fundamentally, ovules are the same thing as animal ovum, or eggs. This is the embryo sac.
Pericarp Pericarp is the thickened ovary wall that we call fruit. Plants use fruit flesh to protect the seeds, furnish young seedlings with nutrients, and to encourage seed dispersal by herbivores. There are three different types of pericarp tissue: exocarp (outer skin), mesocarp (flesh), and endocarp (inner layer). The dominant pericarp tissue can become hard, as with nuts, or fleshy, as we see in peaches and avocados. In some cases, we eat the pericarp. In others, we eat the seed. When we eat the pericarp, we call it a fruit - but not always.
Placentae The place where the ovules and the pericarp connect is called the placentae. If you look inside a tomato, the seeds are growing inside the placental area. The placenta also has an outgrowth, called an obturator, that feeds and guides the pollen tube.
Plants are classified by where their ovaries are found within the pistil, relative to the attachment of the petals and sepals. This point of attachment is called the insertion point. Ovaries can be superior, half-inferior, or inferior, and their flowers are described as hypogynous, perigynous, or epigynous, respectively.
Inferior ovaries To say a plant has inferior ovaries is not a genetic slur. Instead, it refers to fruits in which the seeds are located below the other floral parts, within the hypanthium. The hypanthium is a cuplike structure at the base of a flower, that surrounds or is attached to the gynoecium. The gynoecium (‘woman’s house’) is the female part of a flower, or pistil. Pumpkins, squash, cucumbers, pomegranates, bananas, pears, and apples have inferior ovaries.
Superior ovaries Superior ovaries are no better than other ovaries, they are simply found above the insertion point. Legumes, such as peas and beans, true berries, and plants that produce drupes, such as blackberries, raspberries, and soapnuts, feature superior ovaries.
Half-inferior ovaries Half-inferior ovaries are surrounded by the receptacle, with parts equally above and below the insertion point. Some botanists take this classification to the extreme, by saying a plant has a “two-fifth inferior ovary” but I think that’s taking things a bit far. Peaches, nectarines, and crape myrtles are in this group.
Take a look at the flowers in your garden that are destined to become fruits and nuts. Where is all the action taking place? Can you tell?
Most people know that ‘deciduous’ refers to trees that lose their leaves each year, but there is more to the word and the process than meets the eye.
When a plant no longer needs a flower’s petals, those petals are allowed to fall away. When fruit becomes ripe, it is also allowed to drop. This act of ‘allowing to fall away’ is at the heart of deciduousness. Did you know that a deer’s antlers and your own baby teeth are also considered deciduous?
Pros and cons of deciduousness
Unlike evergreens, deciduous trees and shrubs, and some herbaceous perennials, lose their leaves each year. This is called abscission. In the Northern and Southern hemispheres, leaf drop normally occurs in autumn or early winter. In tropical regions, deciduous plants lose their leaves during the dry season. In each case, leaf loss occurs at a time when having leaves is not in the plant’s best interest. For example, broad-leafed hardwood trees might collect too much snow or ice in winter, causing limbs to break off, leaving open wounds, while tropical plants are unable to maintain heavy leaf cover without rainfall. This annual leaf drop is believed to be a mechanism by which some plants interrupt pests and disease triangles. It also means a plant must have enough food stored to last through the winter and to begin growing again in spring.
Another benefit of abscission is related to something called cavitation. Cavitation refers to times when water tension within a plant becomes so great [think rainy season] that the sap vaporizes within the tree and the oxygen held in that water expands rapidly enough to cause a loud ‘crack’ - you may have heard this, if you spend any time in forests. The problem with cavitation is that it damages the xylem. Plants can usually repair this damage, but not aways. One way deciduous plants protect themselves against cavitation is by dropping their leaves, which, in turn, allows them to have larger xylem vessels. These larger xylems allow deciduous plants to take up more water than evergreens in the summer months.
The chemistry of deciduousness
During spring and summer months, deciduous plants are busy producing chlorophyll, a green pigment. Shorter days (or drought stress) trigger plant hormones (auxins) to reduce chlorophyll production and to start drying the connection between the stem and petiole of each leaf. In some cases, the plant also withdraws the nitrogen and carbon held in those leaves for use in spring. Lower levels of the green pigment are what allow us to see other colors. Some of these colors, the yellow, brown, and orange carotenoids are always present, while red and purple anthocyanins are produced in autumn, as sugars become trapped in the leaves. These changes are triggered by shorter days and cooler nights. In areas without those conditions, the leaves simply dry up and fall off.
Deciduous trees and shrubs
Common deciduous trees include almond, pomegranate, quince, apricot, nectarine, peach, olive, persimmons, plum, fig, pear, walnut, and apple. Your grapes, kiwi, blackberries, raspberries, strawberries, and blueberries are also deciduous. In fact, nearly all fruit and nut crops occur on deciduous plants, citrus being a notable exception.
Winter is the best time to prune deciduous trees. [Except apricot and cherry, due to eutypa dieback.] The absence of leaves makes it easier to see the true structure of deciduous trees and shrubs, allowing you to see and remove dead, diseased, crossed, and poorly placed limbs. Winter is also the best time to apply dormant oil, to control many pests, such as scale.
Have you ever been to a family reunion and wondered how that one cousin could possibly be related to everyone else? Well, it happens in plant families, too.
Learning about plant families can help you generalize about plant care, potential problems, and best practices. It also makes you sound really smart when talking with others about their garden and landscape struggles and successes.
If nothing else, learning about the basic edible plant families can help you make the best choices when it comes to crop rotation.
This list is, by no means, exhaustive, but it provides a good starting point.
How many plant families are growing in your garden?
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.]
One way plants store food and reproduce is with a structure called a corm.
Different types of geophytes
Corms are similar to bulbs, tubers, and rhizomes, in that they are all geophytes. Geophytes are structures that store food and water. If you cut these structures in half, however, they look very different.
Each corm is a segment of underground stem that includes at least one growing bud. Corms are often covered with a papery coating called a tunic. The tunic is made out of dead petiole sheaths that were produced the previous year. The tunic protects the corm against insect and animal feeding, flooding, and drought. The inside of a corm is tissue filled with carbohydrates. The flat bottom is where roots emerge and cormels are produced. In some cases, the parent corm is used up completely and is replaced by the cormels it produced. In other cases, the corm simply becomes larger. In yet other cases, a new corm grows from the top of an old one that withers and flattens. Over time, this type of corm ends up becoming a stack of used up corms.
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?
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.
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, kiwi fruit, 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.]
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.
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 where trees seal 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.
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!
In the world of plant names, science rules.
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 Phillip came over from Great Spain. Or, make 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!
In the world of plants, climbers have access to more sunlight and better airflow than many of their low-growing neighbors. Plus, these climbers don’t have to invest time and resources into generating a substantial trunk. Most people believe that all climbing plants are vines of one sort or another, but that is not accurate. There is an entirely separate category of climbing plants known as bines.
Bines or vines?
Vines use specialized stems (suckers and tendrils) to grab tiny handholds on their support, be it a fence, cattle panel, or a tree. Bines grow skyward by winding shoots into a helix around a support. Some people claim that bines spiral in a specific direction because of residing in the northern or southern hemispheres, but the direction of growth is species specific, rather than based on location.
Common bine plants
There are several bines commonly found in gardens and landscapes. The most common garden bines include:
Which bines are growing in your garden?
You can grow a surprising amount of food in your own yard. Ask me how!