Date: Sun, 28 May 2000 09:37:15 -0700 From: Ivan Snyder <bioexp@juno.com> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg1646$foo@default> Subject: re: Sundew Evolution
Hi Jan and all,
Ivan started:
>>Here is an idea. Often we see tentacles in Drosera where only sticky
>>trichomes should be, on the scape and bracts. I have seen a few times
>>sundew malformities where flower styles and tentacles had been fused
>>together, and also tentacles replacing styles.
Jan replied:
>Are you sure you have observed tentacles? The histological structure
>of these is quite different from styles/stigmas, and tentacles are
>usually not formed on the ovary.
Quite sure, some were fully formed and functional. I will try to preserve
them next time for you. Might this make you a believer?
>>This has led me to believe
>>that perhaps this is how tentacles evolved in sundews. Consider that
>> styles are protein sensitive and capable of movement.
>AFAIK, the styles of Droseraceae are not capable of movement. Have
>you made other observations?
Styles are sensitive to protein ( pollen grain surface ). As you know, I
do much cross pollination. Flowers close up quickly, but I remove petals
to expose, so I have witnessed movement. Check it out.
>>Maybe the first
>>sundew had simple glandular trichomes united with styles? If all this
is
>>true, then the same genes involved in construction of styles in Drosera
>>will also be expressed in tentacle construction. Anyway, maybe we
should
>>not just compare trichomes with tentacles, but instead compare
tentacles
>>to styles.
>I have a different theory (cf. CPN 26: 34-38, 1997): I believe the
>glands on the bracts and calyces of Plumbaginaceae-Plumbaginoideae
>(likewise Nepenthales but probably more primitive) represent suitable
>models for the precursors of the carnivorous glands in Nepenthales.
>These Licopolian glands are in turn probably derived from simpler
>structures in Tamaricaceae. From their microscopic anatomy, these
>multicellular glands are much more homologous to each other than any
>of them is to styles or stigmas.
I read it. Perfectly plausible, and no major conflict with the idea
suggested above. My idea merely shows where the traits may have come
from. I see from your CPN article that you understand the principle of
translocation and reinscribed function. The beauty of our ideas is that
the ancestral plant had all the traits needed for carnivory. They only
needed to be reorganized.
Ivan Snyder
Hermosa Beach
California
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