5 differences between monocots and dicots
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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:1. The first angiosperms had pollen with a single furrow or pore through the outer layer (monosulcate). This feature is retained in the monocots, but most dicots are descended from a plant which developed three furrows or pores in its pollen (triporate). 2. After male meiosis, each pollen mother cell splits into a rounded tetrad of four haploid nuclei before cell wall formation
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:DICOTS Dicot plants differ in structures of their seeds, foliage and flowers, from the monocotyledons. They can be easily distinguished by studying their distinct characteristics. Let us learn about each feature of the dicot plants in detail. Seed The most important difference between the monocots and dicots is the number of embryonic leaves, or cotyledons. There are two cotyledons in the seeds of dicot plants that actually emerge above the soil, when the seed germinates. They then turn green and form the first two leaves of the new plant. Leaves The leaves of the dicot plants have veins that form a branched pattern, unlike monocots, in which they run parallel. The veins are actually netted or webbed on the whole surface of the leaf, in dicot plants. Vascular Structure The stems of dicot plants have vascular bundles, consisting of two structures, the xylem and the phloem. The xylem helps to transport water and minerals from the root to the other parts of the plant and the phloem transports food that is made in the leaves, to the storage organs. These vascular bundles are arranged in a circular manner around the edge of the stem. Flowers The flower parts of dicot plants are usually present in fours or fives. Sometimes, they are found in multiples of either numbers. These flower parts include petals, sepals and pistils, or the reproductive parts of the plant. Roots Roots of dicot plants are often fibrous and branched. They branch out in many smaller parts that form a dense network of root system, unlike monocot plants, that have a tap root system. SEE HERE http://library.thinkquest.org/3715/seeds.html http://www.ucmp.berkeley.edu/glossary/gloss8/monocotdicot.html http://www.howtoorganicgarden.com/new_page_2.htm
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