. A textbook of botany for colleges and universities ... Botany. 6i8 ECOLOGY Besides the various species of Vroscra, other members of the same family, as Drosophyllum, have irritable glandular hairs. Two of the most remarkable genera are Aldrovanda and Dionaea, which have sensitive leaf blades that close suddenly when irritated, and prevent the escape of alighting insects (figs. 657-659). Im- pact upon the stiff outer part of certain hairs is perceived by delicate cells beneath and transmitted to the region where movement is effected. The secretion of digestive fluids, and subsequent digestion
. A textbook of botany for colleges and universities ... Botany. 6i8 ECOLOGY Besides the various species of Vroscra, other members of the same family, as Drosophyllum, have irritable glandular hairs. Two of the most remarkable genera are Aldrovanda and Dionaea, which have sensitive leaf blades that close suddenly when irritated, and prevent the escape of alighting insects (figs. 657-659). Im- pact upon the stiff outer part of certain hairs is perceived by delicate cells beneath and transmitted to the region where movement is effected. The secretion of digestive fluids, and subsequent digestion and absorption take place as in Drosera. Pitcher plants. — The pitcher plants {Sarracenia, Nepen- thes, etc.), like Drosera, commonly are bog plants. The pitcher-like leaf blades of Sarracenia (fig. 908) are partly filled with rain water, into which insects, by chance or attracted by the bright colors, frequently wander and are drowned. For crawling insects, entrance is easy and exit difficult by reason of stiff downward-pointing hairs at the edge of the pitcher. In Nepenthes (fig. 656) nectar is secreted at the pitcher edge, doubtless forming an addi- tional attraction. Proteolytic enzyms have been discovered in the pitchers of Nepenthes, the glands occurring at the base of cavities and consisting of spherical multicellular structures, below which are the terminal tracheids of a conductive bundle, as in Drosera. Enzym secretion prob- ably does not occur in Sarracenia, though it is possible that the products of insect decay may enter the plant, much as in saprophytes. In Dischidia, an epiphytic pitcher plant, there are double pitchers, one inside the other; the outermost pitcher is a sort of living flower pot in which earth and water collect and into which adventi- tious roots penetrate from other parts of the plant. BuUerworts and bladder-worts. — A third family of carniv- orous plants is represented by the butterworts (Pinguicula) and the bladderworts (Utricularia), whic
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910
