Pitcher Plants

Pitcher-Plants, the isolated genus Nepenthes, belonging to the Indian monsoon region, and other plants (such as the Australian member of the saxifrage family Cephalotus follicularis, and the American Sarraceniaoeae) in which the leaf is modified into an ascidium or pitcher. Though varying in details, the pitcher generally develops by intercalary tubular growth, like a peltate leaf. In the Sarraceniaoeae it is sessile; in Cephalotus, shortly petiolate; in Nepenthes, furnished with a long and partly winged petiole. The apical part of the leaf-blade commonly forms a raised lid to the pitcher, and its margin is often strengthened by inrolling. Remarkable external flanges sometimes exist, and these and the mouth of the pitcher may be baited by honey-secreting glands. Internally the throat of the pitcher is generally smooth; but lower down are downward-pointing hairs and a surface studded with glands. Some of these glands excrete a neutral watery liquid. In Nepenthes, as soon as any insects or other nitrogenous matter has found its way into this liquid, it becomes acid, digestive ferments (zymases) are discernible, and a true digestion takes place, resulting in formation and absorption of peptones. In the Sarraceniaoeae, though the liquid seems to have a remarkable asphyxiating effect upon insects, like oil rather than water, no digestion seems to take place, the leaf merely absorbing the liquid products of decomposition. In Dischidia, it would seem, the function is altogether distinct, water-storage rather than insect-eating being aimed at.