una at doliolum.biology.yale.edu
Mon Oct 17 20:19:47 EST 1994
NEC95ISA09 at mecn.mass.edu writes:
>... primative plants, i.e., Liverworts, Hornworts, and moss are
>considered to be ancestors to blue green algae.
It's the other way around: the algae came first. In any case,
modern liverworts, hornworts, and mosses are not "primitive";
they've been around longer, and are therefore just as evolved
as other plants. They are less complex, morphologically, but
simplification is an important part of evolution in many groups.
>... they are nonvascular plants which mean they live in moist,
"Nonvascular" means lacking a particular tissue adapted for
water transport. Not all nonvascular plants live in moist or
shady places: some live in extremely dry, hot environments.
>... gametophytes are produced which produce sporophytes. ...
The vascular plants also show this alternation of generations.
For the rest, a botany or paleobotany textbook will give many
details about what we believe the early atmosphere was like.
The story is a bit too elaborate to reproduce here in a brief
fashion (and anyway I'd be extracting it from a textbook).
Una Smith una.smith at yale.edu
Dept. of Biology, Yale Univ., New Haven, CT 06520-8104
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