Vegetative Morphology

Vegetative Morphology

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 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. 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 pea- like 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. 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. 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 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. 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.

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