Dionaea muscipula J.Ellis

Kew Species Profiles

General Description

Venus flytrap 'eats' insects and sometimes even small frogs that become trapped in its modified, toothed leaves. If the prey struggles, the trap will close even tighter.

Kew's Director Joseph Hooker and Charles Darwin shared a keen interest in carnivorous plants. Darwin even described Venus flytrap as 'one of the most wonderful plants in the world'.

Species Profile

How the flytrap works

The workings of the trap mechanism in Dionaea are complex and depend on changes in the osmotic potential of the cells in the hinge. The traps close when one or other of the trigger hairs is touched more than once in quick succession; if nothing is caught, traps reopen after about a day. Once an insect is trapped, flaps close tighter to squash it, and enzymes are secreted to digest the prey. Mucilage is secreted to seal the margins of the trap. Some days later, after the insect is digested, the trap reopens.

The traps are unusual in that they spring shut. Similar traps are found in the aquatic genus Aldovandra (also in the family Droseraceae), but these only catch minute aquatic animals. Most species of Drosera (sundews) also catch insects, but by using sticky hairs that cover the leaf, after which the leaf slowly coils over the insect before digesting it.

A hand-coloured engraving of Dionaea muscipula by Sydenham Edwards, taken from Curtis's Botanical Magazine (1804) Geography and distribution

Venus flytrap is found in south-east USA, in North Carolina and South Carolina. Populations, probably exotic, have been recorded from New Jersey and Florida.

Description

Leaves: Venus flytrap has a rosette of leaves up to 20 cm across. Each leaf has a flat stalk and ends in a trap about 2 cm across. The centre is often reddish, and the sides of the trap are lined with 14-20 stiff, comb-like bristles that interlock when the trap closes.

Flowers: The flowers are white, in a cluster at the top of a 15-45 cm leafless stalk. The flowers have five sepals and five equal petals, around 12 mm long. There are 15-20 stamens.

Fruits and seeds: Numerous, small black seeds are formed in a round capsule.

Threats and conservation

Dionaea muscipula is Vulnerable (VU) (A1acd, B1+2c) according to IUCN Red List criteria. It is also considered Vulnerable (G3), using NatureServe criteria. It has a narrow range on the coastal plain of North and South Carolina. The species is threatened by over-collection from the wild but to an even greater degree by loss of habitat and fires, which alter its natural habitat. Dionaea muscipula is listed on Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), which mandates regulations on international trade in threatened species.

Dionaea muscipula was among 250 rare and threatened plants selected for inclusion in the first IUCN Plant Red Data Book published in 1978. This publication grew out of pioneering work by a handful of botanists in Kew's Herbarium, which recognised that there are many plant species in danger of extinction for which their plight was less publicised than rare and charismatic animals.

A network of researchers was established around the world, feeding data on the conservation status of plants to the team at Kew, making up what was then called the Threatened Plants Committee (TPC). This work formed the basis of the plant database of the UNEP World Conservation Monitoring Centre, which records distribution and conservation status of over 34,000 globally rare and threatened plant species and modern day IUCN Red List of Threatened Species.

Uses

Venus flytrap is commonly grown as a curiosity and is a source of wonder for children and adults alike. Indeed, it is likely that Venus flytrap has been the source of inspiration for many a horror film involving man-eating plants - a somewhat unique 'use' within the plant kingdom! Dionaea muscipula has also been shown to contain naphthoquinones that may have medicinal value.

This species at Kew

Dionaea muscipula  can be seen in the Princess of Wales Conservatory in the carnivorous plant zone.

The botanical artist Marianne North depicted  Dionaea muscipula  in her painting  North American Carnivorous Plants , which can be seen in the Marianne North Gallery.

Distribution

USA

Ecology

Bogs and pine barrens.

Conservation

Vulnerable (VU) according to IUCN Red List criteria. Listed in Appendix II of CITES.

Hazards

Carnivorous - insects and other small bugs beware!