60 LEAF-CLIMBERS. Cuap. II. 
proofs that the petioles in a state of nature are excited 
to movement by very slight pressure. Jor instance, 
I have found them embracing thin withered blades 
_ of grass, the soft young leaves of a maple, and the 
flower-peduncles of the quaking-grass or Briza. The 
latter are about as thick as the hair of a man’s 
beard, but they were completely surrounded and clasped. 
The petioles of a leaf, so young that none of the leaflets 
were expanded, had partially seized a twig. Those of 
almost all the old leaves, even when unattached to any 
object, are much convoluted ; but this is owing to their 
having come, whilst young, into contact during several 
hours with some object subsequently removed. With 
none of the above-described species, cultivated in pots 
and carefully observed, was there any permanent 
bending of the petioles without the stimulus of contact. 
In winter, the blades of the leaves of C. vitalba drop 
off; but the petioles (as was observed by Mohl) 
remain attached to the branches, sometimes during 
two seasons; and, being convoluted, they curiously 
resemble true tendrils, such as those possessed by 
the allied genus Naravelia. The petioles which have 
clasped some object become much more stiff, hard, and 
polished than those which have failed in this their 
proper function. 
Trop£oLum.—I observed T. tricolorum, T. azwreum, 
T. pentaphyllum, T. peregrinum, T. elegans, T. tuberosum, 
and a dwarf variety of, as I believe, T. minus. 
Tropxolum tricolorum, . var. grandiflorwm.—The 
flexible shoots, which first rise from the tubers, are 
