60 LEAF-CLIMBERS. Chap. II. 



proofs that the petioles in a state of nature are excited 

 to movement by very slight pressure. For 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 G. 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^eolum. I observed T. tricolorum, T. azureum, 

 T. pentaphyllum, T. peregrinum, T. elegans, T. tuberosum, 

 and a dwarf variety of, as I believe, T. minus. 



Tropseolum tricolorum, var. grandiflorum. The 

 flexible shoots, which first rise from the tubers, are 



