Re[2]: Tuber vs. Corm

From: alistair_hay at rbgsyd.gov.au on 1999.01.15 at 15:40:23(2902) My 2 cents worth!!: I agree with Wilbert on the whole. No bulbs (storage in persistent leaf bases and/or scale leaves) in Araceae known to me (Typhonodorum the nearest???). Most common morphological terms were invented for the depauperate flora of Europe. Even the most fundamental terms such as stem, leaf and root, let alone corm/tuber/rhizome, do not always work as clear cut categories in tropical plants. Corm and tuber and rhizome intergrade in Araceae. I would think that corm and tuber are at least sometimes interchangeable terms in say Amorphophallus, and that tuber and rhizome are at least sometimes interchangeable terms in say Colocasia. Alocasia produces corm-like bulbils!!! This is no help at all! Rigorous definitions, when they are really needed, have to be developed purposefully on a case by case (e.g. family by family or genus by genus) basis (though that creates interesting problems if structure needs to be codified in order to define the group). `Corm' to an Iridaceae person is likely to be a different thing from corm to an Araceae person. This doesn't necessarily matter. Pronunciation is a free-for-all, but make it BEAUTIFUL to other people. Most plant names are worth savouring - even Amorphophallus! Alistair Hay +More ______________________________ Reply Separator _________________________________ Subject: Re: Tuber vs. Corm Author: at mailgate Date: 12/1/99 19:45 At 06:58 PM 1/11/99 -0600, you wrote: >I was talking with a Ph.D Botanist (name withheld for obvious reasons) who >is a recognized authority on different types of bulbs.... He said, when I >asked him, that Amorphophallus is a corm and not a tuber or bulb. I think >he said something about the cell structure..... > >Do we want to start this discussion again....??? > >Which is it? >Dewey > >Dewey E. Fisk, Plant Nut >THE PHILODENDRON PHREAQUE >Your Source for Tropical Araceae > > Dewey: I don't know what definition your botanist was using, but I define a corm as a compressed, usually subterranean, modified stem that is surrounded by dry, scale-like leaves. A tuber is a thickened, compressed, more or less fleshy, usually underground stem. Using these definitions, the modified underground stems of the species of Amorphophallus are tubers. I have not seen any evidence of the modified stems being surrounded by dry, scale-like leaves. The problem is that some of the tubers have a corm-like shape with a large apical bud. From what I have seen of the genus, the underground stems are quite varied. Some look very much like a rhizome, some look like the "typical" tuber, and others look like corm. We are looking at a continuum here, and definitions, at least simple ones that you learn in school, usually only cover the usual, most common conditions. The thing that I think is important is looking at the range of modifications, then I think that it is obvious that they are tubers. That is this Ph.D.'s two-cents worth. Paul M. Resslar Professor of Biology Virginia Wesleyan College 1584 Wesleyan Drive Norfolk, Virginia 23502-5599 U.S.A.

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