Caap. I. TWINING PLANTS. 43 
case of variability in “Fulmer’s dwarf forcing-bean,” 
which occasionally produced a single long twining 
shoot. 
Solanum duleamara 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 
(tom. 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 Hoya carnosa revolve 
