The Physics Factbook™
Edited by Glenn Elert -- Written by his students
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|Rendle, Alfred Barton. The Classification of Flowering Plants. Britain: Cambridge University Press, 1930.||"Genera over 400; species 17,000. Widely distributed in the temperate and warmer parts of the world."||17,000 species|
|"Orchids." The World Book Encyclopedia. 14th ed. New York: World Book, 1990.||"There are over 20,000 species of these plants."||20,000 species|
|Allaby, Michael. Plants and Plant Life. Volume 9 Flowering Plants: The Monocotyledons. Danbury, Connecticut: Grolier, 2001.||Number of Genera: 796
Number of species: 17,500
|Spellenberg, Richard. The Audubon Society Field Guide to North American Wildflowers. New York: Random House, 1979.||"The 600-700 genera and 20,000 species are most abundant in the tropics, where they most frequently grow upon other vegetation."||20,000 species|
|Orchidaceae, The Orchid Family. BBC Gardening.||"The orchid family includes nearly 900 genera, somewhere between 20,000 and 30,000 species and over 70,000 hybrids or cultivars."||20,000- 30,000 species|
The Orchid Family or orchidaceae are the largest family of angiosperms, or flowering plants in the world. Approximately twenty thousand species and nine hundred genera of orchids are known. The numbers of species vary from anywhere between fifteen thousand to thirty thousand and the number of genera range from seven hundred to one thousand. The orchidaceae consists of three subfamilies: apostasioideae, cyprepioideae, and cypripedium. Orchids can be saprophytic herbs, terrestrial, or epiphytic. In general, orchids are most abundant in the tropics and subtropics, but they are also common in the temperate latitudes. The tropical species are mainly epiphytic, meaning they are found growing above ground, usually perched in trees. In Australia and North America, the orchids are mainly terrestrial. They grow in the soil, and emerge each season to reproduce. The largest species of orchids are the spotted coral root. They are saprophytes, which live of decaying leaves. Wild orchids grow in all parts of the world except Antarctica. The largest number of orchids comes from Asia.
Orchids are considered monocots because they only have one leaf that first emerges from the seed. Also, monocots typically have flower parts that are grouped in three or six, which is exemplified by the orchid. The orchid is irregular with its three sepals that are organized under and between its three petals. There are two lateral petals and a third petal that is single and different from the others because it forms a saclike lip or slipper, which is distinctive and common to most of the species of orchids. Orchids have bulbous or thick tuber-like roots. This specific characteristic is what gave Orchids their name. These tubers resembled paired testicles and in the Greek language, "orchis" (ορχις) means "testicle".
Orchids are considered the most evolved of the flowering plants. The structure, the fragrance and the color of these plants have evolved to help them in the process of reproduction. The orchid's development of unique structures often permits cross- pollination only by specific pollinators and the relationships are highly specialized. Each orchid species will germinate and grow only under certain conditions. Pollen is usually held together in masses and in many cases must be positioned correctly on the insect for pollination of another flower to occur. This tends to prevent cross-pollination between different species. An orchid's fragrance, size and color may attract certain types of insects or birds as well. Orchids are very unique in their methods of fertilization, seed production, germination, and pollination strategies. Orchid seeds are so tiny that they need help from certain types of fungi. In order to germinate the orchid seed must be penetrated by fungus threads. These fungi supply the seeds with the substances they need to grow. The pollination processes of orchids have fascinated botanists for centuries.
Bianca Nicoletti -- 2003
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