IAS Aroid Quasi Forum

About Aroid-L
 This is a continuously updated archive of the Aroid-L mailing list in a forum format - not an actual Forum. If you want to post, you will still need to register for the Aroid-L mailing list and send your postings by e-mail for moderation in the normal way.

  Tuber vs. Corm
From: plantnut at macconnect.com (Dewey Fisk) on 1999.01.11 at 16:54:07(2879)
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

+More
From: Don Burns <burns at mobot.mobot.org> on 1999.01.11 at 17:08:38(2881)
> Do we want to start this discussion again....???
>

Yes, I would like to see this discussion resume. The definitions of the
two were nebulous when I studied (probably a poor choice of words) high
school biology. And I remain confused to this day.

What are acceptable definitions of the two? And then where/how does
Amorphophallus fit into each?

Don

+More
From: MOTO_DO at t-online.de (Ihr Name) on 1999.01.12 at 17:20:49(2883)
First of all how do you define a corm, did you mean the botanical
terminus "cormus"?
If yes, then in my opinion the corm is the wrong word.
+More
From: "Dr. C. R. Waldron" <cwaldron at frognet.net> on 1999.01.12 at 17:39:07(2886)
------ =_NextPart_000_01BE3E0B.2D6049C0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

+More
From: Paul Resslar <presslar at mailhost.vwc.edu> on 1999.01.12 at 17:44:07(2887)
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

+More
From: Wilbert Hetterscheid <hetter at vkc.nl> on 1999.01.13 at 07:18:56(2890)
I suggest we file this discussion somewhere, so that it doesn't
resurface all the time. My two Euro-cents:

Bulb: this is a condensed stem or stem part, INCLUDING all appendages!
Therefore a bulb shows e.g. scales, which are modified leaves, used for
storage (Lilium!), or storage scales and some outer, thin, protective
scales (Iris, Crocus). Obviously no aroid exists (....I hope...) that
shows such a device. Quite often, bulbs also contain the new season's
growth in condensed form (inflorescence etc.).

Tuber: modified stem or stem part, for storage WITHOUT appendages (or
non-modified ones). So, in a bulb, the appendages form the main storage
facility, wheras in a tuber, the stem (-part) itself swells and performs
the storage function. Therefore a tuber has no thickened appendages but
may have thin scales protecting buds or whatever. A tuber may contain
more than one growth-module (e.g. some Anchomanes species) or just one
(Amorphophallus).

+More
From: Jmh98law at aol.com on 1999.01.13 at 13:16:00(2893)
In a message dated 1/13/99 7:07:15 AM Pacific Standard Time, hetter@vkc.nl
writes:

<< I suggest we file this discussion somewhere, so that it doesn't

+More
From: goroff at idcnet.com (Iza & Carol Goroff) on 1999.01.13 at 13:24:44(2894)
I believe that a corm shows cylindrical symmetry about a vertical axis,
whereas a tuber does not.

Iza Goroff

+More
From: Jonathan Ertelt <jonathan.ertelt at vanderbilt.edu> on 1999.01.14 at 15:19:32(2900)
>This question was discussed at some length last fall on a gesneriad growers
>listserve - one member found the following definitions on the web:
>
>On the GardenWeb site (http://www.gardenweb.com/glossary/):
>
>Corm: The enlarged fleshy base of a stem, bulb-like but solid.
>
>Tuber: A thickened and short subterranean branch having numerous
>buds or eyes and used for food storage.
>
>
>
+More
From: alistair_hay at rbgsyd.gov.au on 1999.01.15 at 07:40:23(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
Note: this is a very old post, so no reply function is available.