Observations suggest that most Pothos
are root climbers sensu Schimper (1903). However, it is nearly impossible
to ascertain whether the plants remain in contact with the ground
throughout their life cycle or whether for at least some of the
time they lose contact with the ground, i.e. that they are hemiepiphytes
(see Putz & Holbrook, 1986; Croat, 1990).
Field observations suggest that the function of the eocaul (see
Boyce & Hay 1998) is to locate a climbing host on which to establish
juvenile shoots. It is apparent that once this function is satisfied
the eocaul soon withers. The question is unanswered whether the
eocaul always dies before the juvenile shoot sends down feeder roots
and re-establishes contact with the ground or whether there is a
period when the plant is separated from the ground. If the latter,
then many Pothos
species should be classed as secondary hemiepiphytes
(see Putz & Holbrook, 1986).
Of species I have observed P. grandis
seems habitually to spend at least some of its life free from the
ground and thus should be called a secondary hemiepiphyte. However,
this observation is based on a very few plants in one area of limestone
in which there were few sizeable trees. Habitat data for P.
from other localities suggests that degraded woodland
on steep limestone is an atypical habitat for the species and thus
my observations are based on an atypical set of ecological circumstances.
Part of the problem with life form observations is that it is seldom
easy to trace a mass of interlaced adherent stems back to a single
source of ground contact and virtually impossible to ascribe the
points of ground contact to a particular time in the plants