Sarraceniaceae

▪ plant family

      family of pitcher plants (pitcher plant) that belong to the order Ericales and are native to North and South America. These low-growing perennial herbs are notable for their pitcherlike leaves, which are specialized for trapping insects. The family consists of three genera: Sarracenia, with eight or nine species; Heliamphora, with five or six species; and Darlingtonia, with one species.

      The Sarraceniaceae are unlike any other plants in the Western Hemisphere. They derive their common name from their hollow tubular leaves, which can take the form of a trumpet, a pitcher, or an urn. These leaves are carefully constructed pitfalls that entrap insects or other tiny prey that are lured to the leaf's mouth by glistening surfaces or unusual light-transmitting patches. The lip of the leaf pitcher is beset with stiff, downward-pointing hairs or other devices to prevent the insect from crawling out after it has entered. Exhausted, the insect eventually settles into the digestive liquor at the bottom of the pitcher. Protein-digesting enzymes and bacterial activity release nitrates and other useful nutrients from the insect's body, which are absorbed by the pitcher plant to supplement the meagre nutrient supply of its environment (or the insects may be eaten by animals living in the pitchers).

      Pitcher plants commonly inhabit bogs, swamps, wet or sandy meadows, or savannas where the soils are water-saturated, acidic, and deficient in nitrates or phosphates. They are herbaceous perennials. Instead of an upright, above-ground stem, the pitcher plant usually has a short, round, horizontal underground stem (rhizome) from which leaves radiate outward and upward. The mature rhizome, which is 8 to 30 cm (3 to 12 inches) long, grows for 10 to 30 years, depending on the genus. Most members of the family produce a crop of pitchered, insect-catching leaves in the spring, and a second crop of leaves, some of which are tubeless, in the fall. The leaves vary in colour from yellow green to dark green suffused with red. The leaves are clearly adapted to function like flowers in attracting insects; they are flowerlike in their striking colour patterns and shapes, and during their active period in the summer, glands in them exude nectar drops containing fructose, which is highly attractive to some insects.

      The name pitcher plant typically refers to members of the genus Sarracenia, which is confined to eastern North America and is concentrated in northern Florida and the southern parts of Georgia and Alabama. The yellow pitcher plant (S. flava) is probably the most abundant species within this area. By contrast, the common pitcher plant (S. purpurea) has a much wider range—from Labrador and Great Bear Lake (near the Arctic Circle) to subtropical Florida. The cluster of leaves produced by species of Sarracenia ranges in size from 10 cm (4 inches) in S. rubra to more than 120 cm (4 feet) in S. leucophylla. The habitat of Sarracenia species ranges from sand and gravel along stream banks to wet meadows and savannas. S. rubra, the sweet pitcher plant, can grow in shade; all other species thrive in full sunlight.

      The other North American genus, Darlingtonia, includes only D. californica, the California pitcher plant. It ranges from Oregon to northern California and thrives in redwood and red fir forests to 2,000 metres (6,000 feet) above sea level, where temperatures remain below about 18 °C (65 °F). Its overarching spotted hood and a unique landing ramp that extends from the top of the curiously twisted tubular leaf account for its common name of cobra plant, or cobra lily (cobra plant). Using the landing projection, insects often enter the mouth of the pitcher from the side of the domed hood. Translucent areas in the hood encourage potential prey to approach the rim of the pitcher. Insects often fly against these “windows” and fall into the liquor at the pitcher's bottom.

      The third genus, Heliamphora, grows in the rainforest mountains of Guyana and Venezuela. Its species form cushions on ridge crests and mingle with sphagnum moss in swampy depressions. The stems of some species of Heliamphora rise to more than 120 cm (48 inches) and are branched and slightly shrubby. Their pitchers attain a height of 50 cm (20 inches).

      Besides flowerlike leaves, all pitcher plants produce flowers that are showy and have an agreeable scent. The solitary, nodding flowers are borne on long stalks; in Heliamphora several flowers may be borne together. The flowering stalk scarcely rises above the leaves in Sarracenia species but is longer in Darlingtonia and Heliamphora. The flowers' petals are usually five in number, and the stamens are numerous and shed pollen copiously.

      Pitcher plants' showy leaves, their large, colourful, and scented flowers, and their nectars attract many kinds of insects, but especially bees, which are the chief pollinators. The fruits are dry capsules that shed their seeds. Some pitcher plants can also propagate vegetatively. In Darlingtonia, and less often in Sarracenia, buds arise at nodes (stem joints) in the rhizome and grow into new plants, giving rise to slowly spreading colonies.

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