Life on Lan7 - known living species Whence came the...

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Life on Land Perhaps the greatest change in the terrestrial life of the Cretaceous was the rise and diversification of the flowering plants, the angiosperms . The angiosperms, the last of the seed plant groups to evolve, appeared over 140 million years ago during the the beginning of the Cretaceous. All members of this group 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
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Unformatted text preview: known living species. 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? Click here to view an online lab exercise in phylogeny and try to figure things out! 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 paleobotanist David Dilcher and his associates at the Florida Museum of Natural History....
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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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