[Taxacom] paleodicots

[Thomas G. Lammers]

At 02:06 PM 2/22/2010, Kenneth Kinman wrote:
>But weren't the paleodicots always thought of as dicots primarily
>because of their dicotyledonous seedlings?

Yes.  But in many of the other characters traditionally used to distinguish 
the two, they fail.  There is a great deal of trimery in flowers of these 
families (a supposed monocot character), despite "4's or 5's or multiples 
thereof" being the dicot standard.  Some like Piperaceae have scattered 
vascular bundles when the stem is viewed in cross-section, a supposedly 
monocot character.

I agree that a fundamental dichotomy is a nice thing to have.  But about 5% 
of our species belong to lineages whose origin pre-date that event.

I just think its one of those places where we traditionalists can concede 
to a cladistic view without really causing ourselves any problem.

If we were to depict phylogeny in a Besseyan fashion instead of a Hennigian 
one, I could see a little blob at base (the basal lineages or "monosulcate 
dicots") with two large blobs arising, the monocots and dicots (triaperurates).


Thomas G. Lammers, Ph.D.

Associate Professor
Curator of the Neil A. Harriman Herbarium (OSH)
Department of Biology and Microbiology
800 Algoma Blvd.
University of Wisconsin Oshkosh
Oshkosh, Wisconsin 54901-8640 USA

e-mail:     lammers at uwosh.edu
phone:      920-424-1002

Plant systematics; classification, nomenclature, evolution, and 
biogeography of the Campanulaceae s. lat.

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