WINTER ADAPTATION OF OPUNTIA.—The Ohio species of cactus, Opuntia
humifusa Raf., has an interesting habit which seems to be a protective
measure against cold. At the approach of Winter the flattened stems lose
their upright position and press themselves closely to the surface of
the ground.
The stems lose considerable of their moisture at the same time, becoming
wrinkled but not at all flaccid. By the end of April they are again
upright and distended.