Chap. I. TWINING PLANTS. 43 



case of variability in " Fulmer's dwarf forcing-bean," 

 which occasionally produced a single long twining 

 shoot. 



Solatium dulcamara is one of the feeblest and 

 poorest of twiners : it may often be seen growing as 

 an upright bush, and when growing in the midst of 

 a thicket merely scrambles up between the branches 

 without twining; but when, according to Dutrochet 

 (torn. xix. p. 299), it grows near a thin and flexible 

 support, such as the stem of a nettle, it twines round 

 it. I placed sticks round several plants, and vertically 

 stretched strings close to others, and the strings alone 

 were ascended by twining. The stem twines in- 

 differently to the right or left. Some others pecies 

 of Solanum, and of another genus, viz. Habrothamnus, 

 belonging to the same family, are described in horti- 

 cultural works as twining plants, but they seem to 

 possess this faculty in a very feeble degree. "We may 

 suspect that the species of these two genera have as 

 yet only partially acquired the habit of twining. On 

 the other hand with Tecoma radicans, a member of a 

 family abounding with twiners and tendril-bearers, but 

 which climbs, like the ivy, by the aid of rootlets, we 

 may suspect that a former habit of twining has been 

 lost, for the stem exhibited slight irregular movements 

 which could hardly be accounted for by changes in the 

 action of the light. There is no difficulty in under- 

 standing how a spirally twining plant could graduate 

 into a simple . root-climber ; for the young internodes 

 of Bignonia Tweedyana and of Soya camosa revolve 



