Re: pinhole Botany help - cotyledon vs endosperm?

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From: Karen Kalumuck (karenk@exploratorium.edu)
Date: Thu May 02 2002 - 14:21:15 PDT 

Message-Id: <v01540b08b8f75d81079c@[192.174.3.119]>
Date: Thu, 2 May 2002 14:21:15 -0700
From: karenk@exploratorium.edu (Karen Kalumuck)
Subject: Re: pinhole Botany help - cotyledon vs endosperm?

Hi Ben!

It is confusing! I've looked in a number of sources, and sometimes the
endosperm is visible, sometimes the fleshy area appears to be labeled as
cotyledon. You do indeed have your definitions correct. I believe that
the confusion arises from the stage of development of the seed that has
been drawn/photographed. The embryo inside the seed develops extensively
prior to germination. Initially, there's lots of endosperm visible, and
small cotyledons. Before germination, the embryo grows and the cotyledons
can get quite large -- such as what you're seeing in the bean seeds. Just
prior to germination, most of the endosperm may have already been consumed
by the developing embryo.

Hope this helps!

Karen K.

Karen E. Kalumuck, Ph.D.
Biologist
Exploratorium Teacher Institute
3601 Lyon St.
San Francisco, CA 94123
415-561-0388
karenk@exploratorium.edu

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