Vegetative Morphology

Transcription

1 Vegetative Morphology Plant identification frequently makes use of features of the vegetative, or non-reproductive, parts of a plant, such as the stem and leaves. To describe a plant, start with leave structure - the shape of the leaf, how the leaf is arranged (i.e. alternate or opposite) and how it attaches to the stem (i.e. stalkless or clasping). Leaf Shape Leaf Arrangement Leaf Attachment to Stem

2 Reproductive Morphology Plant family can sometimes be determined by examining the flower structure (i.e. number of petals and/or sepals) or the reproductive parts of the plant (i.e. number /arrangement of stamens). Floral appendages are thought of as making up as many as four whorls of appendages, attached to a compressed axis, the receptacle. The outermost whorls (perianth) are sterile, and comprise the calyx (made up of sepals) and corolla (made up of petals). When sepals and petals cannot be distinguished from each other the perianth members may be referred to as tepals. Stamens and pistils make up the two central whorls of the flower, known as the androecium and gynoecium, respectively. The androecium comprises the stamens in which pollen is produced. The gynoecium comprises one or more pistils, within the ovary of which fertilization occurs and seeds are matured.

3 Pea Family (also known as the Legume or Bean Family: Leguminosae) Key Words: "banner, wings, and keel". Pea-like pods, often with pinnate leaves If you have seen a pea or bean blossom in the garden, then you will be able to recognize members of the Pea family. These are irregular flowers, with 5 petals forming a distinctive "banner, wings, and keel", as shown in the illustration. The banner is a single petal with two lobes though it looks like two that are fused together. Two more petals form the wings. The remaining two petals make up the keel and are usually fused together. The proportions of the parts may vary from one species to another, but as long as there is clearly a banner, wings and keel, then the plant is a member of the Pea family. Pea-like pods are another distinctive trait of the family. For practice, look at a head of clover in the lawn. You will see that each head is a cluster of many small Pea flowers, each with its own banner, wings, and keel. As the flowers mature each one forms a tiny pealike pod. I'll bet you never noticed that before! The Pea family is very large, with 600 genera and 13,000 species worldwide, all descendents of the very first Pea flower of many millions of years ago. Over time the Peas have adapted to fit many different niches, from lowly clovers on the ground to stately trees that today shade city sidewalks. Families this large often have subgroupings called subfamilies and tribes. It works like this: The most closely related species are lumped together into a single group or "genus". For example, there are about 300 species of clover in the world. Other members of the pea family include: Lupine, Prairie Clover, Trefoil, Alfalfa.

4 Mustard Family (also known as Cruciferae) Key Words: 4 petals and 6 stamens--4 tall and 2 short. Mustard flowers are easy to recognize. If you have a radish or turnip blooming in the garden, then take a close look at the blossoms. When identifying flower parts, it is best to start on the outside of the flower and work towards the middle like this: sepals, petals, stamens, and pistil(s). On the outside of the mustard flower you will see 4 sepals, usually green. There are also 4 petals, typically arranged like either the letters "X" or "H". Inside the flower you will see 6 stamens: 4 tall and 2 short. You can remember that the stamens are the male part of the flower because they always "stay men". The female part is the pistil, found at the very center of the flower. For the purposes of the Mustard family, all you need to remember is "4 petals with 6 stamens--4 tall and 2 short". If you find that combination in a flower, then you know it is a member of the Mustard family. Worldwide there are 375 genera and 3200 species. About 55 genera are found in North America.

5 All species of Mustard are edible, although some taste better than others. In other words, it doesn't matter which species of mustard you find. As long as you have correctly identified it as a member of the Mustard family, then you can safely try it and see if you want it in your salad or not. Most members of the Mustard family are weedy species with short lifecycles like the radish. Look for them in disturbed soils such as a garden or construction site, where the ground is exposed to rapid drying by the sun and wind. Common invasives include Dame s Rocket and Garlic Mustard. The Mustards sprout quickly and grow fast, flowering and setting seed early in the season before all moisture is lost from the ground. Also be sure to look closely at a Mustard seedpod, called a silicle or silique, meaning a pod where the outside walls fall away leaving the translucent interior partition intact. They come in many shapes and sizes, as you can see in the illustration, but they always form a raceme on the flower stalk, which looks something like a spiral staircase for the little people. With practice you can easily recognize the mustards by their seed stalks alone, and from fifty feet away. Identification by the seed stalks is helpful since many of the flowers are too small to peer inside and count the stamens without a good hand lens. Interestingly, six of our common vegetables--cabbage, cauliflower, kohlrabi, Brussels sprouts, broccoli, and kale--were all bred from a single species of mustard, Brassica oleracea. Plant breeders developed the starch-storage abilities of different parts of the plant to come up with each unique vegetable. Commercial mustard is usually made from the seeds of the black mustard (B. nigra) mixed with vinegar. As you become more familiar with this family, you will begin to notice patterns in the taste and smell of the plants. While each species has its own unique taste and smell, you will soon discover an underlying pattern of mustardness. You will be able to recognize likely members of the family simply by crushing the leaves and smelling them. Dame s Rocket Garlic Mustard Brassica oleracea

6 Aster or Sunflower Family (also known as the Composite Family: Compositae) Key Words: Composite Flowers in disk-like heads The uniqueness of the Aster or Sunflower family is that what first seems to be a single large flower is actually a composite of many smaller flowers. Look closely at a sunflower in bloom, and you can see that there are hundreds of little flowers growing on a disk, each producing just one seed. Each "disk flower" has 5 tiny petals fused together, plus 5 stamens fused around a pistil with antennae-like stigmas. Look closely at the big "petals" that ring the outside of the flower head, and you will see that each petal is also a flower, called a "ray flower", with it's petals fused together and hanging to one side. Plants of the Aster family will have either disk flowers or ray flowers, or both. When the seeds are ripe and fall away, you are left with a pitted disk that looks strikingly like a little garden plot where all the tiny flowers were planted. The green things outside the flower head that might look like sepals are actually "bracts" (modified leaves) surrounding the disk. The true sepals have been reduced to small scales, or often transformed into a hairy "pappus", or sometimes eliminated altogether. One of the best clues for identifying members of this family is to look for the presence of multiple layers of bracts beneath the flowers. In an artichoke, for instance, those are the scale-like pieces we pull off and eat. Most members of this family do not have quite that many bracts, but there are frequently two or more rows. This is not a foolproof test, only a common pattern of the Aster family. Next, look inside the flower head for the presence of the little disk and ray flowers.

7 Even the common yarrow, with its tiny flower heads, usually has a dozen or more nearly microscopic flowers inside each head, and the inside of a sagebrush flower head is even smaller. Keep in mind that many members of this family have no obvious outer ring of petals, including sagebrush. The Asters are the largest family of flowering plants in the northern latitudes, with 920 genera and 19,000 species found worldwide, including 346 genera and 2,687 species in the U.S. and Canada. Only the Orchid family is larger, but it is mostly restricted to the tropics. Many species of the Aster family are cultivated as ornamentals, including Marigold, Chrysanthemum, Calendula, and Zinnia. Surprisingly few are cultivated as food plants other than lettuce, artichoke, endive, plus the seeds and oil of the sunflower. The Aster family consists of two subfamilies. The Dandelion subfamily includes a variety of plants with dandelion-like flowers. The ray flowers typically over-lap all the way to the center. The petals have strap-like, parallel edges with squared-off ends. The stems and leaves of all species have milky juice, and all are edible, but bitter. Bitter substances like dandelion greens are helpful as an appetizer to stimulate digestive secretions before the main meal. Eating your dandelions can help reduce problems with indigestion later. Keep in mind that there are many other plants with milky juice that are not related to Dandelions, including some that are poisonous. Be sure to check the blossoms for proof. The Aster subfamily is much larger, made up of eleven tribes, some of them radically different from the others. Thistles and knapweed are found in the Artichoke tribe. The Chamomile tribe includes the most aromatic members of the Aster family, such as sagebrush, yarrow, tansy, and of course, chamomile. As a kid I encountered many different species of sage (Artemisia). There are 19 species just in Montana. But without a patterns approach to go by, I didn't have a clue where to start, so I brought each specimen to the university herbarium for identification. These days, when I see a new fuzzy green-gray plant, I immediately crush a leaf and smell it to test for a sage-type smell. Each species smells different, but there is a common pattern to the smell that is undeniably sage-like. I also test for members of the Sunflower tribe by smell. Most species are resinous, much like pines, useful medicinally for their expectorant properties. Crush up the head of a sunflower and smell it to get a sense of the resin odor. Once you learn the patterns of smell from the various families, subfamilies and tribes, you will be able to accurately identify many new plants with just your nose. Dandelion Bull Thistle New England Aster

8 Mint Family (also known as Labiatae) Key Words: Square stalks and opposite leaves, often aromatic. If you pick a plant with a distinctly square stalk and simple, opposite leaves, then it is very likely a member of the Mint family. Be sure to smell it too, since many species of the family are loaded with aromatic volatile oils. The rich, spicy quality of these plants makes them useful in cooking, and nearly half the spices in your kitchen come from this one family, including basil, rosemary, lavender, marjoram, germander, thyme, savory, horehound, plus culinary sage (but not sagebrush!), and of course mint, peppermint, and spearmint. For the beginning botanist, that is all you really need to remember: "square stalks with opposite leaves, and usually aromatic". Worldwide there are about 180 genera in the Mint Family representing some 3500 species. Approximately 50 genera are found in North America. Medicinally this family is rich in volatile oils, especially menthol, often used as the penetrating vapors in cough drops. These spicy oils are stimulating and warming, causing the body to open up and sweat; so most of these plants are listed as diaphoretic in herbal books. This property can help you break a fever. A fever is the body's way of "cooking" the microorganisms that cause infections. Using a diaphoretic herb can help raise a mild fever just high enough to "cook" a virus, thus "breaking" or ending the fever. Volatile oils are also highly lethal to

9 microorganisms. On camping trips I often use aromatic Mints to help purify questionable water. Eating a few Mint leaves after drinking from a creek certainly won't kill everything in the water, but it sure helps. You can safely sample any member of the Mint family. Some species like the Coleus, a house plant with red and green leaves, have no aroma at all, while a patch of the more potent Agastache may bring tears to your eyes just passing through. Note that there are a handful of other plants with square stems and opposite leaves, which may be confused with the Mints. Those plants are found in the Loosestrife, Verbena and Stinging Nettle families, but none of them smell minty. As you become proficient at identifying members of the Mint family by their square stalks, opposite leaves, and spicy aroma, you should also familiarize yourself with the flowers. Notice in the illustration that there are 5 sepals, all fused together so that only the tips are separate. The 5 petals are also fused together, but note how asymmetrical or "irregular" the flowers are, compared to the more symmetrical or "regular" Mustard flowers. Some Mint flowers are much more irregular than others, but if you study them closely you will see that they typically have 2 petal lobes up and 3 petal lobes down. Inside the flower there are 4 stamens, with one pair longer than the other. As you learn these patterns of the Mint family you will be able to recognize and use them anywhere in the world. Anise Hyssop Slender Mountain Mint Bergamont