Cuap. IL. TEN DRIL-BEARERS. 85 
Mohl, who includes under the name of tendrils various 
organs haying 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 :—Bignoniacex, Polemoniacexr, Legu- 
nuinose, Composite, Smilacex, Fumariacee, Cucurbitacee, 
Vitacex, Sapindacex, Passifloracex.* 
transformed into branches, as with 
certain Papilionaceous plants. 
(5.) Plants with their branches 
forming true tendrils, and used 
exclusively for climbing—as with 
Strychnos and Caulotretus. Fyen 
the unmodified branches become 
much thickened when they wind 
round a support. I may add that 
Mr. Thwaites sent me from Ceylon 
a specimen of an Acacia which 
had climbed up the trunk of a 
rather large tree, by the aid of 
tendril-like, curved or convoluted 
branchlets, arrested in their 
growth and furnished with sharp 
recurved hooks. 
* As far as I can make out, the 
history of our knowledge of 
tendrils is as follows:—We have 
seen that Palm and von Mohit 
observed about the same time the 
singular phenomenon of the spon- 
taneous revolving movement of 
twining-plants. Palm (p. 58), I 
presume, observed likewise the 
revolving movement of tendrils; 
but I do not feel sure of this, for 
he says very little on the subject. 
Dutrochet fully described this 
movement of the tendrilin the 
common pea. Mohl first discover- 
ed that tendrils are sensitive to 
contact; but from some cause, 
probably from observing too old 
tendrils, he was not aware how 
sensitive they were, and thought 
that prolonged pressure was neces- 
sary to excite their movement. 
Professor Asa Gray, in a paper 
already quoted, first noticed the 
extreme sensitiveness and rapidity 
of the movements of the tendrils 
of certain Cucurbitaceous plants. 
