In this plant I once observed a main branch after it
had caught a stick become spirally flexuous in 7 hrs., and spirally
contracted in 18 hrs. Generally the tendrils of the Echinocystis
begin to contract in from 12 hrs. to 24 hrs. after catching some
object; whilst unattached tendrils do not begin to contract until two
or three or even more days after all revolving movement has ceased.
A full-grown tendril of Passiflora quadrangularis which had caught a
stick began in 8 hrs. to contract, and in 24 hrs. formed several
spires; a younger tendril, only two-thirds grown, showed the first
trace of contraction in two days after clasping a stick, and in two
more days formed several spires. It appears, therefore, that the
contraction does not begin until the tendril is grown to nearly its
full length. Another young tendril of about the same age and length
as the last did not catch any object; it acquired its full length in
four days; in six additional days it first became flexuous, and in
two more days formed one complete spire. This first spire was formed
towards the basal end, and the contraction steadily but slowly
progressed towards the apex; but the whole was not closely wound up
into a spire until 21 days had elapsed from the first observation,
that is, until 17 days after the tendril had grown to its full
length.
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