In a third case both lateral branches which
ought to have been modified into tendrils, produced flowers like the
central branch, and had quite lost their tendril-structure.
I have seen, but was not enabled carefully to observe, only one other
climbing Sapindaceous plant, namely, Paullinia. It was not in
flower, yet bore long forked tendrils. So that, Paullinia, with
respect to its tendrils, appears to bear the same relation to
Cardiospermum that Cissus does to Vitis.
PASSIFLORACEAE.--After reading the discussion and facts given by Mohl
(p. 47) on the nature of the tendrils in this family, no one can
doubt that they are modified flower-peduncles. The tendrils and the
flower-peduncles rise close side by side; and my son, William E.
Darwin, made sketches for me of their earliest state of development
in the hybrid P. floribunda. The two organs appear at first as a
single papilla which gradually divides; so that the tendril appears
to be a modified branch of the flower-peduncle. My son found one
very young tendril surmounted by traces of floral organs, exactly
like those on the summit of the true flower-peduncle at the same
early age.
Passiflora gracilis.
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