Rotting Tubers/ Just in from the garden

[Bush, Gene]

Hello,
I remembered my Arisaema triphyllum (pale green form from local
woods) sitting almost on top of the ground out in the garden. Went out
and lifted the original mature tuber- about 3 inches across. There is
also one about half that size and both are covered with the beginning of
offsets. The depression in the ground also has several smaller past
years offsets. When I picked up the original tuber the bottom came off
in a sheet looking like wrinkled brown tissue paper. Bottom of the tuber
was smooth and light in color. Second in size was wrinkled on the bottom
, again resembling tissue paper,  but still held firm to the tuber. I
did not check the smaller offsets.
I do not see any indications of a tuber rotting away to be replaced,
but rather an old skin being sloughed off like a snake and this is the
bottom of the tuber only. Offsets are what seems to push them apart.
Incidentally, the tubers sit literally in an open hole in the ground
that they have formed. There is no soil around the tuber until you get
to the outside rim and bottom.
Gene Bush    Munchkin Nursery     Southern Indiana     Zone 6a
genebush at munchkinnursery.com
AR>Rand, Tom, Guy, Simon et al,

AR>I'm totally surprised to hear that some have found that rotting away of the
AR>bottom of a planted tuber and replacement by a new tuber is part of the
AR>natural process of growth of at least some arisaemas.

AR>I have been under the apparently erroneous impression that arisaema tubers
AR>continue to enlarge each year, and that only the roots are "annual". In fact
AR>isn't this the main criterion that some have brought to bear in the debate
AR>about whether arisaemas are tubers or corms?

AR>I must admit that I have seldom, if ever, dug up a healthy arisaema in the
AR>fall, and if I have, have never seen the phenomenon that has been described,
AR>where a new tuber arises like a phoenix from the rotting "ashes" of the past
AR>year's growth. That certainly doesn't seem the case in the first few growth
AR>cycles in pots, which I've seen many times.

AR>Let's have some more input on this.

AR>Jim McClements