Ch. 4: Tendril Bearers (cont.)

CUCURBITACEAE.
Homologous nature of the tendrils
Echinocystis lobata, remarkable movements of the tendrils to avoid seizing the terminal shoot
Tendrils not excited by contact with another tendril or by drops of water
Undulatory movement of the extremity of the tendril
Hanburya, adherent discs
VITACAE
Gradation between the flower-peduncles and tendrils of the vine
Tendrils of the Virginian Creeper turn from the light, and, after contact, develop adhesive discs
SAPINDACEAE
PASSIFLORACEAE
Passiflora gracilis
Rapid revolving movement and sensitiveness of the tendrils--Not sensitive to the contact of other tendrils or of drops of water--Spiral contraction of tendrils--Summary on the nature and action of tendrils.

CUCURBITACEAE.--The tendrils in this family have been ranked by competent judges as modified leaves, stipules, or branches; or as partly a leaf and partly a branch. De Candolle believes that the tendrils differ in their homological nature in two of the tribes. [29] From facts recently adduced, Mr. Berkeley thinks that Payer's view is the most probable, namely, that the tendril is "a separate portion of the leaf itself;" but much may be said in favour of the belief that it is a modified flower-peduncle. [30]

Echinocystis lobata.--Numerous observations were made on this plant (raised from seed sent me by Prof. Asa Gray), for the spontaneous revolving movements of the internodes and tendrils were first observed by me in this case, and greatly perplexed me. My observations may now be much condensed. I observed thirty-five revolutions of the internodes and tendrils; the slowest rate was 2 hrs. and the average rate, with no great fluctuations, 1 hr. 40 m. Sometimes I tied the internodes, so that the tendrils alone moved; at other times I cut off the tendrils whilst very young, so that the internodes revolved by themselves; but the rate was not thus affected. The course generally pursued was with the sun, but often in an opposite direction. Sometimes the movement during a short time would either stop or be reversed; and this apparently was due to interference from the light, as, for instance, when I placed a plant close to a window. In one instance, an old tendril, which had nearly ceased revolving, moved in one direction, whilst a young tendril above moved in an opposite course. The two uppermost internodes alone revolve; and as soon as the lower one grows old, only its upper part continues to move. The ellipses or circles swept by the summits of the internodes are about three inches in diameter; whilst those swept by the tips of the tendrils, are from 15 to 16 inches in diameter. During the revolving movement, the internodes become successively curved to all points of the compass; in one part of their course they are often inclined, together with the tendrils, at about 45 degrees to the horizon, and in another part stand vertically up. There