Dormancy and Cold Strat. - J. McClements, E. Hornig, GRS

[George R Stilwell, Jr.]

A late reply to Edouardo. There are apparently a few species of Arisaema
(notably A. thunbergii ssp urashima) which have a dormancy period. In
fact,
the above species seems to require two cold periods, if planted outside,
before appearing.

It may be that it will form a radicle as soon as the inhibitors are
leached
away from the seed surface, but a cold interval is needed before top
growth
occurs.

Jim McClements

My experience with this species is different from Jim's - the seeds I
was given (originally from NCSU arboretum) germinated and grew, top
and bottom, at 70F, like most other arisaemas.  I always presoak
seeds (c.48 hours) but don't think this is removing growth inhibitors -
I think it's just speeding up water uptake.  Unsoaked seeds seem to
take a couple of weeks longer to germinate.

Ellen Hornig

Reading Guy Gusman's last listing, I realize that I neglected to mention
the trait of A. thunbergii ssp. urashima to not send up a leaf the first
year, as Guy notes. But, it doesn't need cold strat to germinate. The
cormlet develops very nicely without a leaf. Perhaps this is the source
of all the confusion.

On occasion, I've had this happen with other species as well. I've
learned not to throw away pots just because they had no leaves showing
the first season.

Ray
GRSJr at Juno.com