Date: Sun, 17 Dec 2000 09:04:55 -0800 From: Ivan Snyder <bioexp@juno.com> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg3628$foo@default> Subject: re: CP Evolution Tidbits
> Very interesting your theory, but sorry I am not so convinced yet...
:-)
I agree about the absortive cotyledons of Drosera and Dionaea. It
hapens in Drosophyllum and Aldrovanda as well, as I have noticed in my
recent investigations. Thus, the seedlings retain usually one of the
cotyledons inside of the sead coat, producing enzymes to degrade the
nutrients (starch, in this case) and so absorbing them. It is noticed
when we note the cotyledon cells with huge nucleus, this way indicating
the high metabolic activity. I have some photos taken using microscope,
I can send some if you are interested.
You say about some "nubs" at the cotyledon tips. In my study, I
could not see this one. Did you observe yourself or you saw in any
paper?
Best regards
Vitor.
Hi Vitor and all,
Thankyou kindly for your reponse to my evolution theory and also for your
additional information. I can imagine a plant growing in very wet
conditions might have its cotyledons still active in enzyme production
and absorptive capacity. There are many non-carnivorous plants having
defensive sticky glands. Byblis has these sticky glands on their
cotyledons. I have tested the cotyledons on Byblis and they are
carnivorous. So maybe Byblis began with only rudimentary carnivorous
cotyledons having sticky glands which accidentally captured tiny insects
and perhaps stray pollen, and then later elaborated upon this.
Drosophyllum (the most primitive sundew?) also has long cotyledons the
same shape as its leaves. It has been awhile since I have grown
Drosophyllum but I think I recall this plant also having retentive glands
on the cotyledons. Drosophyllum might be the ideal plant in which to
study this phenomena since it displays cryptocotylar germination. Thus
the cotyledons do in fact digest and absorb nutrients for a prolonged
period after sprouting.
I have seed of Drosera rotundifolia sprouting now and the mentioned
nubs can be viewed with a 20 power lens just after the seed coats have
been cast off. As the coyledons enlarge the nubs disappear.
Ivan Snyder
Hermosa Beach
California
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