example for parallel venation in leaves
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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:Monocotyledonous Plant Orders & Their Families http://www.floresflowers.com/taxa/Monocots.html http://www.pierce.ctc.edu/biology/EMbuja/BIOL203/Monocots.htm Dicot plant families & their genera http://www.floresflowers.com/taxa/Dicots.html Pick you plants and look them up on Zip Code Zoo. For example the palm tree family Arecaceae are monocots. Cocos nucifera (Coconut Palm) http://zipcodezoo.com/Plants/C/Cocos_nucifera/
Answers:Yes. There is always a fourth line that can pass through the three nonparallel lines. I'm sure this could be proven using equations, but I am using a purely conceptual argument. Brief explanation: If you can stand at a point on one line as see the other two lines cross anywhere in the distance, then you can draw a fourth line through all three. The only instance where two lines in 3-D space could appear to parallel is if you could approximate a perfect projection of that 3-D space into 2-D. In other words, they look parallel from one angle but not others. This can never happen since your vantage point is always a point. You will always be at an angle relative to that perfect projection. Long explanation: Recall first of all, that in two dimensions, two lines that are not parallel must intersect, and vice versa. Now imagine that you are able to place yourself within the three-dimensional world where these three lines exist and look at them from any vantage point you like. Remember, that when you look at something from a distance, you see a two-dimensional picture. We can also think about projecting the three-dimensional space onto two dimensions from various vantage points. For example, using cartesian coordinates (x, y, and z axes), we can imagine making a projection which would see a plane containing the Y and Z axes as a line. One way to think of this is as if you were looking at the cartesian world from a distance and you were sitting on the Z axis. You might see the X axis as a horizontal line, and the Y axis as a vertical line. You would not be able to tell that the plane in front of you was a plane because you would be IN the plane. Here is the key concept that will be used to prove the point. If you are able to place yourself at any point on any line and see the other two lines intersect, then by definition, there is a line that will intersect all three, and it will pass through the intersection points you view in the other two lines, as well as the point at which you are located. Using this rule try to imagine any configuration that would allow you to see the other two lines as not intersecting from EVERY point on the third line and repeating this test for all three lines. I will argue, this is impossible. We are left considering only the case where from the vantage of a a point on one line, the other two lines appear parallel. Not strictly possible, but let s leave that aside and consider projections first. We know that we can define a 2-D projection in which two nonparallel lines appear parallel. Let s call these lines 1 and 2. Let s also say that in a projection in which the plane containing both the Y and Z axes appears as a line, that lines 1 and 2 are parallel not only to each other, but also to the Y axis. For simplicity, let s say that in this projection, line 1 is coincident with the Y axis, and line 2 intersects the X axis at a point we will call +1. Let s review. In our projection, we see two vertical lines, one of which coincides with the vertical Y axis, and the horizontal X axis. Since we know these lines are not parallel in 3-D, then we know that any projection that does not see the Y-Z plane as a line will also not show lines 1 and 2 as parallel, but rather as intersecting. Since we defined our lines as both intersecting the X axis, then if we look at a projection along the X axis, orthogonal to our previous projection, and in which the X-Y plane appears as a line, then we will see lines 1 and 2 intersecting at the intersection of the Y and Z axes. Now can any third line be drawn in such a way that from any point on that line the other two lines appear parallel. I think to some this answer is intuitively clear, but let s try to flesh it out. First, is there any vantage point from which lines 1 and 2 look parallel? We could argue that from a distance on a third line we might approximate what it looks like to project the other two lines onto 2-D, and that as for the projection, we will see them as parallel only if we also see the Y-Z plane as parallel. Therefore also, if any part of line 3 extends far out of the Y-Z plane, then from those parts of that line, the Y-Z plane will not appear as a line, but as a plane, and lines 1 and 2 will not appear parallel. Therefore, the only remaining possibility is a line that does not extend far beyond the Y-Z plane. The only ones that fit this criterion (since lines are infinitely long) are ones IN the Y-Z plane or in a plane parallel to it. If it were in the Y-Z plane, then it would by definition have to intersect in space with line 1, since they cannot be parallel. If they intersected, then we could easily draw a fouth line through that intersection point and any point on line 2. Therefore line 3 must be in a plane parallel to the Y-Z plane. Now we have all three lines in planes that are parallel to each other, and our original projection (which sees the Y-Z plane as a line) now sees three parallel lines. Based on our earlier argument, though, all three lines are seen as intersecting in any projection that does not see the Y-Z plane as a line. Using one of the lines in one of the outer two planes, ask yourself if you can look back at the other two lines and ever see them as parallel. The answer is no, because the only time you can ever see them as parallel is in a perfect projection which sees all three planes as lines. Since you cannot be in all three planes, you will necessarily see the other two as planes, and not as lines. Therefore, you cannot possibly see the other two lines as parallel. This also means there is point on this line from which you cannot see an intersection of the other two lines and there will actually be an infinite number of ways to draw line 4 through the other three.
Answers:Aloe vera is an Angiosperm plant . The scientific classification is as under = Kingdom = Plantae ( All plants ) Division = Spermatophyta ( Seed bearing plants ) Sub- Division = Angiospermae ( seed bearing and flowering plants . Besides, the seeds are enclosed in fruits . So seed bearing as well as fruit bearing plants . Class = Monocotyledonae = Single cotyledon in the seed . Floral parts are three in number or in multiple of three ( 6 or 9 ), leaves often show Parallel venation . Kindly click on the link below to learn more about it= http://en.wikipedia.org/wiki/Aloe_vera Click on the links below to learn about Angiosperms = http://en.wikipedia.org/wiki/Angiosperm http://angiosperm-angiosperm.blogspot.com/2007/11/angiosperm.html Thank you !