A. t. urashima timeclock?

Jim McClements, Dover, DE z6 JimMcClem at AOL.COM
Tue Feb 13 16:55:40 CET 2001

While most arisaema seeds can be fooled into growth cycles by "artificial
winters", some seem smarter!

A. thunbergii ssp. urashima not only is one of the arisaemas that require two
cold periods before making a leaf, but also appears to have a built in
"timeclock" which enables it to restrict its growth periods to the
appropriate season of the year.

Here's my latest experience demonstrating this:

1. Seeds collected in late '99 were soaked in a detergent solution for one
hour on 12-9-99 and placed in a moist paper towel at room temperature.

2. By 1-1-00 100% had germinated a radicle and were planted in wet turface,
in standing water, at room temperature.

3. By 4-15-00 no above-ground growth had been noted, and all seeds were found
to have formed small "tuberettes", which were refrigerated in a bag
containing slightly moist turface.

4. On 7-10-00 the tuberettes were again planted in wet turface at room

5. By 11-8-00 no growth was noted, and the pot was removed from the standing
water, allowed to dry out partially and then was bagged and refrigerated.

6. On 2-1-01 the pot was removed from the cold, left in the bag and by 2-12
it appears that all tuberettes are putting up top growth vigorously.

I would point out that this is exactly what would have happened if I had
planted the seeds outside in December of 1999 and left them alone!

Those of us who grow a lot of arisaemas from seed realize that this is the
exception rather than the rule, but I think that as we gain more experience
we realize more and more that some members of this genus don't "sprout like
cress", and some are seemingly near-impossible to grow from seed.

Is anyone really doing well with A. elephas? And do others have as much
trouble with the Himalayan species as I do? I think that the latter problem
may often be due to infertile seeds, and think that perhaps seeds of those
species are more short-lived than usual.

Maybe the way to grow those recalcitrant species is to plant them out and let
nature do its thing!

Jim McClements

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