Pitcher plant

Pitcher plants (or pitfall traps) are carnivorous plants whose prey-trapping mechanism features a deep cavity filled with liquid. Insects such as flies are attracted to this cavity, often by visual lures such as anthocyanin pigments, and nectar bribes. The liquid contained within the pitcher traps and gradually dissolves the body of the insect. This may occur by bacterial action, or be due to enzymes secreted by the plant itself. Furthermore, some pitcher plants contain mutualistic insect larvae, which feed on trapped prey, and whose excreta the plant absorbs. Whatever the mechanism of digestion, the prey items are converted into a 'soup' of amino acids, peptides, phosphate, ammonium and urea, from which the plant obtains its mineral nutrition (particularly nitrogen and phosphorus). Like all carnivorous plants, they occur in locations where the soil is too poor in minerals and/or too acidic for most plants to be able to grow.

Contents

1 Types of pitcher plant 2 Localities 3 Reference 4 External links

Types of pitcher plant

The families of Nepenthaceae and Sarraceniaceae are the best-known and most speciose groups of pitcher plants.

The Nepenthaceae contains a single genus, Nepenthes, containing about 70 species and numerous hybrids and cultivars. In these Old World pitcher plants, the pitchers are borne at the end of tendrils that extend from the midrib of an otherwise unexceptional leaf. The plants themselves are often climbers, accessing the canopy of their habitats using the aforementioned tendrils, although others are found on the ground in forest clearings, or as epiphytes on trees.

In contrast, the New World pitcher plants (Sarraceniaceae), which comprise three genera, are ground-dwelling herbs whose pitchers arise from a horizontal rhizome. In this family, the entire leaf forms the pitcher, whereas in the Asian pitcher plants, the pitcher arises from the terminal portion of the leaf. The species of Heliamphora, which are popularly known as marsh pitchers (or erroneously as sun pitchers), have a simple rolled-leaf pitcher, at the tip of which is a spoon-like structure that secretes nectar. They are restricted to areas of high rainfall in South America. The North American genus Sarracenia are the trumpet pitchers, which have a more complex trap than Heliamphora, with an operculum, which prevents excess accumulation of rainwater in most of the species. The single species in the Californian genus Darlingtonia is popularly known as the cobra plant, due to its possession of an inflated 'lid' with elegant false-exits, and a forked 'tongue', which serves to ferry ants and other prey to the entrance of the pitcher. The species in the genus Sarracenia readily hybridise, making their classification a complex matter.

There are two other genera of pitcher plants, but both contains just one or two carnivorous species.

The Cephalotaceae is a monotypic family with but one genus and species, Cepahlotus follicularis. This species has a small (2 to 5 cm) pitcher similar in form to those of Nepenthes. It occurs in only one location in southwestern Australia.

A few species of bromeliads (Bromeliaceae), such as Brocchinia reducta and Catopsis berteroniana are known or suspected to be carnivorous. Bromeliads are monocots, and given that they all naturally collect water where their leaves meet each other, and that many collect detritus, it is not surprising that a few should have been naturally selected to develop the habit into carnivory by the addition of wax and downward-pointing hairs.

Localities

Pitcher plants occur in a a rather restricted set of locations around the world.

• Sarracenia grow along the eastern seaboard of North America.(Sarracenia purpurea is the official flower of the Province of Newfoundland and Labrador, Canada).
• Nepenthes occur only in South East Asia and Madagascar, and especially in high mountain locations where the climate is cooler and wetter than the surrounding tropical lowlands, for example Mount Kinabalu, Malaysia and Lake Toba, Indonesia. Many species are endemic to particular mountains. A very few species (N. khasiana) are found in India.
• Cephalotus is native to a very small area in the south-west of Australia, around the town of Albany.
• Heliamphora grow only on the Tepuis of Southern Venezuela and Northern Brazil.
• Darlingtonia occur in the North-West United States, mainly the states of Oregon and California.

This restricted range is a reflection of the economic cost of carnivory, as discussed in the main carnivorous plant article.

Reference

• Juniper et al., The Carnivorous Plants, London: Academic Press, 1989.

External links

• Andreas Wistuba, collector of all kinds of pitcher plants (http://www.wistuba.com/)