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Monocots, or monocotyledons, are a class of the flowering plants, or angiosperms. Monocots are named for and recognized by the single cotyledon , or seed leaf, within the seed. The first green blade emerging from the seed upon germination is the cotyledon, which contains sugars and other nutrients for growth until the leaf is able to photosynthesize. Monocots comprise about 67,000 species, or one-quarter of all flowering plants. They include not only the very large grass family (Poaceae, 9,000 species), but also the orchid family (Orchidaceae, 20,000 species), and the sedge family (Cyperaceae, 5,000 species), as well as palms, lilies, bromeliads (including pineapple), and the Araceae, which includes skunk cabbage and philodendron. The angiosperms have traditionally been divided into monocots and dicots alone, but recent work has shown that while monocots form a natural evolutionary group, dicots do not, and so the angiosperms are now grouped into monocots, eudicots , and basal angiosperms. In addition to the single cotyledon in the seed, monocots can be recognized by the arrangement of vascular tissue in the stem. Vascular tissue includes xylem , used for water transport from the roots, and phloem , which carries sugars and other nutrients from the leaves to other tissues throughout the plant. Unlike other angiosperms, whose vascular tissue is arranged in rings around the periphery, the vascular bundles of monocots are scattered throughout the stem. One consequence of this is that monocots cannot form annual rings of hardened tissueâ€”woodâ€”and so are limited in the strength of their stems. Nonetheless, some monocots, notably the palms, do attain significant height. Leaves of monocots have parallel veins, as seen in grass. The roots of monocots also differ from other flowering plants. In monocots, the first root to emerge from the seed dies off, and so no strong, central tap root forms. Instead, monocots sprout roots from shoot tissue near the base, called adventitious roots. The familiar fibrous root system of grasses is an example of this rooting pattern. Many monocots form bulbs, such as onion, gladiolus, and tulips. These are not root structures, but rather modified stems, made of compact leaves. This can be easily seen in the layers of the onion. Most monocot flowers have flower parts in sets of three, so that there may be three or six petals, for instance, along with three egg-bearing carpels and pollen-bearing stamens in some multiple of three. The pollen grains of monocots have a single slit, or aperture, which splits open to allow the pollen tube to grow during fertilization . In contrast, the pollen grain of eudicots has three apertures. Orchid flowers are among the most beautiful and complex of all flowers, due in part to their long and specialized relationship with specific pollinators. Some orchid flowers have evolved to resemble the female of the bee species that pollinates them, luring the male in to attempt copulation. During this process, the pollen, all of which is retained in a single, sticky mass, is transferred to the male bee, who will carry it to the next flower in another fruitless attempt to find a mate. In contrast to the showy orchids, grass flowers are rather simple and dull, in keeping with the absence of any need to attract insects. Grass flowers are suspended at the tip of the plant, where wind can carry the pollen away to land on the female flower of a neighboring plant. Three grassesâ€”corn, wheat, and riceâ€”provide the vast majority of calories consumed by humans throughout the world. Their seeds, called grain, are rich in carbohydrates and contain some protein and vitamins as well. see also Angiosperms; Eudicots; Evolution of Plants; Flowers; Grain; Grasses; Leaves; Roots; Seeds; Shoots Richard Robinson Raven, Peter H., Ray F. Evert, and Susan E. Eichhorn. Biology of Plants, 6th ed. New York: W. H. Freeman and Company, 1999.
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Answers:Grass is the classic example of a monocotyledon plant. The first shoot sent up on germination is a single leaf. A pea is a good example of a dicotyledon. Cotyledon is the first leaf that appears on germination. 'Mono' means one, 'di' means two. The traditional differences between monocots and dicots are: Flowers: In monocots, flowers are trimerous (number of flower parts in a whorl in threes) while in dicots the flowers are tetramerous or pentamerous (flower parts are in fours or fives). Pollen: In monocots, pollen has one furrow or pore while dicots have three. Seeds: In monocots, the embryo has one cotyledon while the embryo of the dicot has two. Stems: In monocots, vascular bundles in the stem are scattered, in dicots arranged in a ring. Roots: In monocots, roots are adventitious, while in dicots they develop from the radicle. slice of onion, showing parallel veins in cross section slice of onion, showing parallel veins in cross section Leaves: In monocots, the major leaf veins are parallel, while in dicots they are reticulate. Not all of these, though, are necessarily definitive. The leaves of most pine trees (which are multicotyledinous) have parallel veins, for example. There is a good picture of a monocot and a dicot seedling side by side here: http://en.wikipedia.org/wiki/Cotyledon
Answers:There's a very easy way to tell whether a plant is dicot or monocot. Look at the veins in the leaf. If they branch out like a tree (dendritic pattern) they are dicots. If the veins are parallel, like the veins in a blade of grass or a corn leaf, it's a monocot. The first link is a pic of an oak leaf, which is a dicot. The second link is a pic of the parallel veins of a corn leaf. Also, dicot flowers tend to have flower parts in multiples of four or five (petals, stamens, sepals). Monocot flowers tend to have flower parts in multiples of threes.
Answers:Monocot is short for monocotyledon which means when the seed germinates one leaf emerges as compared to two with the dicots. Monocots are characterized by parallel venation in the leaves, fibrous root system and flowers with all parts in a multiples of three. Where as dicots have netted venation, typically have a tap root and have flowers with the parts in multiples of four or five. Grasses, palm trees, lilies, iris and orchids are examples of monocots.
Answers:Monocots usually do not have a distinctive palisade and spongy mesophyll. Monocots have parallel veins with a general mesophyll of loosely packed parenchyma cells on both sides of the veins extending to the epidermis layers.