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''Sarracenia'' ( or ) is a genus comprising 8 to 11 species of North American pitcher plants, commonly called trumpet pitchers. The genus belongs to the family Sarraceniaceae, which also contain the closely allied genera ''Darlingtonia'' and ''Heliamphora''. ''Sarracenia'' is a genus of carnivorous plants indigenous to the eastern seaboard, Texas, the Great Lakes area and southeastern Canada, with most species occurring only in the south-east United States (only ''S. purpurea'' occurs in cold-temperate regions). The plant's leaves have evolved into a funnel or pitcher shape in order to trap insects. The plant attracts its insect prey with secretions from extrafloral nectaries on the lip of the pitcher leaves, as well as a combination of the leaves' color and scent. Slippery footing at the pitcher's rim, aided in at least one species by a narcotic drug lacing the nectar, causes insects to fall inside, where they die and are digested by the plant with proteases and other enzymes. ==Morphology == ''Sarracenia'' are herbaceous perennial plants that grow from a subterranean rhizome, with many tubular pitcher-shaped leaves radiating out from the growing point, and then turning upwards with their trap openings facing the center of the crown. The trap is a vertical tube with a 'hood' (the operculum) extending over its entrance; and below it the top of the tube usually has a rolled lip (the peristome) which secretes nectar and scents. The hood itself frequently produces nectar too, but in lesser quantities. The inside of the pitcher tube, regardless of species, can be divided into three to five distinguishable zones: zone 1 is the operculum (or hood), zone 2 is the peristome and rest of the trap entrance, while zones 3 and 4 (which in some species are combined) and 5 (only present in ''S. purpurea'') are further divisions of the actual tube. Each of these zones has a specific function, with corresponding morphophysiological characteristics. *Zone 1: ''Operculum''. In most species the operculum covers at least part of the pitcher opening, thereby preventing rain from excessively filling the pitcher, which would result in the loss of prey and dilute the digestive fluid. The operculum also serves to guide prey to the pitcher opening, using a combination of color, scent, and downward-pointing hairs to guide insects toward the trap entrance. Some species, specifically ''S. minor'' and ''S. psittacina'', have opercula that hang low over the pitcher entrance. These are also studded with chlorophyll-free patches, translucent "windows" which confuse prey into attempting to fly through the operculum, thereby causing them to cascade down the pitcher tube. (A similar, more well developed mechanism is found in the closely related ''Darlingtonia californica''). *Zone 2: ''Peristome and trap entrance''. This zone is composed mainly of the peristome, which produces copious amounts of nectar, luring insect prey to land or crawl onto the perilous footing surrounding the pitcher trap. This zone also includes the waxy upper portion of the pitcher tube. Footing on this zone is especially treacherous, as the waxy deposits on surface of this zone cause unwary insects to lose their footing and tumble into the pitcher depths. *Zone 3: Located below Zone 2, this zone features a leaf surface with non-existent footing, as well as a coating of ultra-fine, downward pointing hairs. Insects that have made it this far lose any chance of escape. It is also studded with digestive glands, which secrete digestive enzymes into the digestive fluid. *Zone 4: This is the final zone in most species. It is filled with digestive fluids, and readily absorbs nutrients released from the insects by the work of the digestive enzymes and bacteria in the pitcher fluid. Along with more digestive glands, this zone features a thick coating of coarse downward pointing hairs, which makes escape from the digestive fluids impossible. *Zone 5: This zone, located below Zone 4 and found only in ''S. purpurea'', is smooth, glabrous, lacks glands, and does not serve as an absorptive zone. Its function is unknown. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sarracenia」の詳細全文を読む スポンサード リンク
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