Nature of tendrils--BIGNONIACEAE, various species of, and their
different modes of climbing--Tendrils which avoid the light and creep
into crevices--Development of adhesive discs--Excellent adaptations
for seizing different kinds of supports.--POLEMONIACEAE--Cobaea
scandens much branched and hooked tendrils, their manner of action--
LEGUMINOSAE--COMPOSITAE--SMILACEAE--Smilax aspera, its inefficient
tendrils--FUMARIACEAE--Corydalis claviculata, its state intermediate
between that of a leaf-climber and a tendril-bearer.

By tendrils I mean filamentary organs, sensitive to contact and used
exclusively for climbing. By this definition, spines, hooks and
rootlets, all of which are used for climbing, are excluded. True
tendrils are formed by the modification of leaves with their
petioles, of flower-peduncles, branches, {24} and perhaps stipules.
Mohl, who includes under the name of tendrils various organs having a
similar external appearance, classes them according to their
homological nature, as being modified leaves, flower-peduncles, &c.
This would be an excellent scheme; but I observe that botanists are
by no means unanimous on the homological nature of certain tendrils.
Consequently I will describe tendril-bearing plants by natural
families, following Lindley's classification; and this will in most
cases keep those of the same nature together. The species to be
described belong to ten families, and will be given in the following
order: --Bignoniaceae, Polemoniaceae, Leguminosae, Compositae,
Smilaceae, Fumariaceae, Cucurbitaceae, Vitaceae, Sapindaceae,
Passifloraceae. {25}

BIGNONIACEAE.--This family contains many tendril-bearers, some