Page:Darwin - On the movements and habits of climbing plants.djvu/72

 represented in the following diagram. This leaf bore nine leaflets; the lower ones are much subdivided. The terminal portion of the petiole, about 1½ inch in length (above the leaflet (f)), is thinner and more elongated than the lower part, and may be considered as the tendril. The leaflets borne by this part are greatly reduced in size, being, on an average, about the tenth of an inch in length and very narrow; one small leaflet measured one-twelfth of an inch in length and one-seventy-fifth in breadth, so that it was almost microscopically minute. All the reduced leaflets have branching nerves, and terminate in little spines like the fully developed leaflets. Every gradation can be traced, until we come to branchlets (as a and d in the figure) which show no vestige of a lamina or blade. Occasionally all the terminal branchlets of the petiole are in this latter condition, and we then have a true tendril.

The several terminal branches of the petiole bearing the