CHAPTER III. 
TENDRIL- BEARERS, 
Nature of tendrils—Bicnontacrg, various species of, and their different 
modes of climbing—Tendrils which avoid the light and creep 
into crevices—Development of adhesive dises—Excellent adapta- 
tions for seizing different kinds of supports—PoLEemonIacEEZ— 
Cobza scandens, much branched and hooked tendrils, their manner 
of action—Lrcuminosm—ComPosirm—SmiLaceEm—Smilax aspera, 
its imefficient tendrils—Fumartacem—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,* and perhaps stipules. 
* Never having had the oppor- 
tunity of examining tendrils 
produced by the modification of 
branches, I spoke doubtfully about 
them in this essay when ori- 
ginally published. But since 
then Fritz Miiller has described 
(Journal of Linn. Soc. vol. ix. p. 
344) many striking casesin South 
Brazil. In speaking of plants 
which climb by the aid of their 
branches, more or less modified, 
he states that the following stages 
of development can be traced: 
(1.) Plants supporting themselves 
simply by their branches stretched 
out at right angles—for example, 
Chiococea, (2.) Plants clasping a 
support with their unmodified 
branches, as with Securidaca, 
(3.) Plants climbing by the ex- 
tremities of their branches which 
appear like tendrils, as is the case 
according to Endlicher with 
Helinus. (4.) Plants with ther 
branches much modified and 
temporarily converted into ten- 
drils, but which may be again 
