corm; was RE: Late fall in Maryland

Russell Stafford, Odyssey Bulbs
Mon, 14 Dec 2009 09:31:54 PST
A corm is by definition a condensed, typically narrow stem comprising 
several nodes and surrounded by a fibrous tunic.  It is 
annual/biennial, developing at the apex of the previous year's 
corm.  Tubers are fleshy annual/biennial structures, which can 
comprise either stem or root tissue, and which do not have a 
tunic.  Stem tubers often form at the tips of stolons.  Tropaeolum 
storage organs are fleshy, have nodes, and lack tunics, so they are 
properly termed stem tubers. Tuberous begonias grow from a perennial 
structure that is in effect a modified hypocotyl.  Technically it is 
neither a corm nor a tuber, although it is usually called the latter.


At 11:13 AM 12/14/2009, you wrote:
>I looked both terms up in the glossary of John Bryan's "Bulbs" revised
>edition.  I don't always blindly trust John, but he did have help putting
>that volume together.
>Corm -- underground storage organ, a swollen part of an underground stem
>Tuber -- underground root modified as a storage organ.

Russell Stafford
Odyssey Bulbs
PO Box 382
South Lancaster, MA  01561

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