Charles Darwin,
The Movements and Habits of Climbing Plants
“ I have seen no instance of two species of the same genus twining in opposite directions, and such cases must be rare; but Fritz Müller [33] states that although Mikania scandens twines, as I have described, from left to right, another species in South Brazil twines in an opposite direction. It would have been an anomalous circumstance if no such cases had occurred, for different individuals of the same species, namely, of Solanum dulcamara (Dutrochet, tom. xix. p. 299) , revolve and twine in two directions: this plant, however; is a most feeble twiner. ”
