From: Clarence Waldron <cwaldron at powersupply.net> on 1998.06.19 at 12:07:14(2341)|
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You are right, Steve--where are those "green" botanists to resolve the =
corm/tuber question. Perhaps we have all become so specialized that no =
one wants to respond for fear that they will be contradicted by some =
eminent "cormologist" or "tuberologist." I guess I'm too old to worry =
about it any more so from a "white" botanist (my research area has been =
mushrooms and other fungi--when you grow mushrooms "green" means =
trouble!) here goes.
Tubers, corms, rhizomes and bulbs are all asexual reproductive organs. =
Bulbs are primarily a leaf structure (there is a small amount of stem) =
typical of lilies, tulips and the classical example--the onion. =
Amorphophallus does not produce bulbs!
Tubers, corms and rhizomes are all stem structures. Rhizomes are =
horizontal stem structures growing at the surface or beneath the ground. =
They may be slender and serve primarily for reproduction (quack grass) =
or swollen by stored food (iris). Generally a tuber is a thickened =
portion of a rhizome (often at the tip of a rhizome) serving for storage =
and bearing nodes and buds--the classic example is the white potato. A =
corm is usually defined as a short vertical rather globose underground =
stem with thin papery leaves on its surface (gladiolus and crocus).
So what are Amorphophallus? I say tubers. If one looks at a konjac in =
the fall one clearly sees rhizomes with enlarged tips, bearing buds, and =
no covering leaf structures. If one chops up the offset tubers each bud =
will produce a new plant just as in potatoes--I've done it! Problem is, =
of course, that some Amorphophallus don't produce rhizomes (or offset =
tubers)--but wait, we just learned that under the right conditions A. =
titanum does. In others (A. odoratus) the "rhizome" is greatly reduced =
so that the tuberous offset appears to be directly on the mother tuber. =
Still, in none of the cases of which I am aware is there an associated =
leaf structure around the enlarged stem to qualify it is a corm.