A manual and dictionary of the flowering plants and ferns / by J.C. Willis.
- John Christopher Willis
- Date:
- 1908
Licence: In copyright
Credit: A manual and dictionary of the flowering plants and ferns / by J.C. Willis. Source: Wellcome Collection.
190/740 page 172
![forming a firm but elastic support, and at the same time dragging the stem upwards and thus economising its materials. The direction of the twist reverses at some point in the spiral; this is a mere mechanical result. To twist a piece of wire, fast at both ends, into a spiral, it will be found necessary to reverse the twist at the middle. Some tendrils, e.g. in Vitis sp., have adhesive discs at the end, others, e.g. in Cobaea, hooks. iendrils, morphologically considered, may be of various natuie stems (usually modified inflorescence-axes), leaves or parts of leaves, or even roots, e.g. the aerial roots of Vanilla and perhaps other plants. Modified stipules form the tendrils of Smilax, &c., modified leaves or parts of leaves those of many Leguminosae (e.g. Lathyrus, Vicia, &c.), Bignoniaceae (e.g. Bignoma) and Cucurbitaceae, Mutisia, Cobaea, Cory- dalis, &c.; modified stem-structures occur in Vitis, Passiflora, Antigonon, Landolphia, &c. A special form of tendril is the sensitive hook that occurs in so many tropical climbers. Inflorescence-axes, modified in structure to form recurved hooks, project from the stem; when a hook catches a sup- port, it clasps it tightly and becomes lignified, e.g. in Arta- botrys, Hugonia, Uvaria, Ourouparia, Unona, Ancistrocladus, Landolphia, Strychnos, Uncaria, &c. Sometimes they are long, thin and flat, and are rolled up like watch-springs, as in some Sapindaceae (Paullinia, &c.), Gouania, Bauhinia, &c. Many plants climb by aid of sensitive leaves. In Glo- riosa, Littonia, &c., the tip of the leaf is sensitive, acting like a tendril. The petiole is often sensitive to contact] usually clasping once round its support, and then frequently becoming woody, e.g. in Tropaeolum, Clematis, Hablitzia, Maurandia, Rhodochiton, &c. Cf. also the leaf-climbers, Fumaria, Adlumia, and Nepenthes (see Part II.). Other plants climb by aid of sensitive lateral branches, which bear ordinary leaves, e.g. Securidaca, Plippocratea, Uvaria, Salacia, Machaerium, &c. Sometimes the branches are leafless and tendril-like, but they are always capable of producing leaves. III. Hook-climbers sprawl over other vegetation, and have hooks, usually recurved, which aid in their support. The only British hook-climbers are Galium and Rubus, both of them with small hooks arising as mere emergences](https://iiif.wellcomecollection.org/image/b28133389_0190.jp2/full/800%2C/0/default.jpg)
