Tendrils, after bending
from a touch, straighten themselves in about two hours, and are then
ready to act again. As soon as they begin to grow old, the
extremities of their two or three pairs of branches become hooked,
and they then appear to form an excellent grappling instrument; but
this is not the case. For at this period they have generally quite
lost their sensitiveness; and when hooked on to twigs, some were not
at all affected, and others required from 18 hrs. to 24 hrs. before
clasping such twigs; nevertheless, they were able to utilise the last
vestige of irritability owing to their extremities being hooked.
Ultimately the lateral branches contract spirally, but not the middle
or main stem.
Lathyrus aphaca.--This plant is destitute of leaves, except during a
very early age, these being replaced by tendrils, and the leaves
themselves by large stipules. It might therefore have been expected
that the tendrils would have been highly organized, but this is not
so. They are moderately long, thin, and unbranched, with their tips
slightly curved. Whilst young they are sensitive on all sides, but
chiefly on the concave side of the extremity. They have no
spontaneous revolving power, but are at first inclined upwards at an
angle of about 45 degrees, then move into a horizontal position, and
ultimately bend downwards.
Pages:
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156