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Darwin, Charles, 1809-1882

"The Movements and Habits of Climbing Plants"


Bignonia aequinoctialis, var. Chamberlaynii.--The internodes, the
elongated non-sensitive petioles, and the tendrils all revolve. The
stem does not twine, but ascends a vertical stick in the same manner
as the last species. The tendrils also resemble those of the last
species, but are shorter; the three toes are more unequal in length,
the two outer ones being about one-third shorter and rather thinner
than the middle toe; but they vary in this respect. They terminate
in small hard points; and what is important, cellular adhesive discs
are not developed. The reduced size of two of the toes as well as
their lessened sensitiveness, seem to indicate a tendency to
abortion; and on one of my plants the first-formed tendrils were
sometimes simple, that is, were not divided into three toes. We are
thus naturally led to the three following species with undivided
tendrils
Bignonia speciosa.--The young shoots revolve irregularly, making
narrow ellipses, spires or circles, at rates varying from 3 hrs. 30
m. to 4 hrs. 40 m.; but they show no tendency to twine. Whilst the
plant is young and does not require a support, tendrils are not
developed. Those borne by a moderately young plant were five inches
in length.


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