Angiosperms are Flowering Plants

Angiosperms are Flowering Plants - efficiency of their...

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Angiosperms are Flowering Plants Flowering plants, the angiosperms , were the last of the seed plant groups to evolve, appearing during the later part of the of the Age of Dinosaurs (the beginning of the Cretaceous, 140 million years ago). All flowering plants produce flowers . Within the female parts of the flower angiosperms produce a diploid zygote and triploid endosperm . Fertilization is accomplished by a variety of pollinators, including wind, animals, and water. Two sperm are released into the female gametophyte: one fuses with the egg to produce the zygote, the other helps form the nutritive tissue known as endosperm. The angiosperms ( angios = hidden) produce modified leaves grouped into flowers that in turn develop fruits and seeds.There are presently 235,000 known living species. Most angiosperms also have larger xylem cells known as vessels that improve the
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Unformatted text preview: efficiency of their vascular systems. Whence came the angiosperms? This was Darwin's "abominable mystery". Clearly angiosperms are descended from some group of Mesozoic-aged gymnosperm seed plant. ...but which one? The classical view of flowering plant evolution suggests early angiosperms were evergreen trees that produced large Magnolia-like flowers. Click here to view an illustration of suggested paths of floral evolution. However, this view has recently been contradicted by the oldest fossil yet found, a 140 million year old plant found by David Dilcher and his associates. The angiosperms underwent an adaptive radiation during the Cretaceous, and for the most part escaped the major extinctions at the end of the Cretaceous....
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This note was uploaded on 11/29/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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