Term for +ACI-handedness+ACI- in Arisaema?

[Pacific Rim Native Plants]

Arisaema spathes wrap sometimes to the right,  sometimes to the
left. Can anyone give me a good botanical term for this? A
picture showing
the phenomenon in A. candidissimum is at
http://www.hillkeep.ca/bulbs%20arisaema.htm.

The cause of this "handedness" also interests me, but I suspect
that is beyond the official realm of discussion on Taxacom. 8-)

Paige Woodward
paige at hillkeep.ca
www.hillkeep.