[Arisaema-l] Arisaema root structure

[Peter Boyce]

Dear Peter,

Correct, no *Arisaema *(indeed no known aroids) are cormous.

A corm is a storage structure as you state. It comprises a main meristem
with laterals at the base

It differs from a bulb in that the bulb lacks a tunic. The bulb consists of
a short stem base bearing one or more buds enclosed in overlapping
membranous or fleshy leaves. Occasionally a bulb has papery covering (e.g.,
*Narcissus*) but that is simply one or more dried out leaves the fleshy
ones of which comprise the main body of the bulb.

A tuber is a modified stem, It has several buds on the surface (think
potato) and if left in the light will turn green owing to activation of
chloroplasts.

A rhizome is also a modified stem, usually elonagted, usually creeping. It
is covered (at least near the active stip) with prophylls and produces
leaves along its length.

Peter

On 24 April 2012 13:54, Peter Taggart <petersirises at gmail.com> wrote:

> Dear Peter,
>
> Are you saying that no, Arisaemas are not corms? and do you agree that the
> structure of a corm is a stem surrounded by modified leaves as well as a
> corm tunic?
>
> How do you define a rhizome? and a tuber?
> Thankyou..
> Peter (UK)
>
>
>
> 2012/4/24 Peter Boyce <phymatarum at googlemail.com>
>
>>  No, because it has no ‘tunic’. Think *Crocus* and *Gladiolus* for true
>> corms. ****
>>
>> ** **
>>
>> Geophytic aroids with underground storage organs are never cormous. Most,
>> regardless of the shape of the storage organ, are tubers. Rhizome has a
>> very specific morphological application and there are none in *Arisaema*that I recall.
>> *Amorphophallus* has two definite rhizomatous species, *A. rhizomatosus*and
>> *A. hayi*.****
>>
>> ** **
>>
>>
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