Pitcher Plants - Woodland Park Zoo Seattle WA

TROPICAL PITCHER PLANTS

Classification and Range

Tropical pitcher plants belong to a very unique group of flowering plants that have special adaptations found in few other plants: pitcher-shaped leaves which trap and digest small organisms. There are approximately 76 species of tropical pitcher plants, all of which are classified in the genus Nepenthes. The genus Nepenthes comprises its own family, the Nepenthaceae, based on floral and other physical characteristics of these plants.

Tropical pitcher plants of the genus Nepenthes are distributed in tropical areas of northern Australia, southeast Asia, southern China, India and Madagascar.

Habitat

These plants grow as vines, in the undergrowth, or up in the canopy of tropical forests.

Physical Characteristics

Tropical pitcher plants generally grow as vines, climbing over other plants, and may grow as epiphytes, growing on other plants in the forest canopy, or as low shrubs. The pitchers of tropical pitcher plants may resemble flowers, but are actually modified leaf blades that hang from coiled tendrils. The pitchers are usually shaped like tubes or, as the name implies, like small pitchers. All species in the genus Nepenthes use their pitchers to trap and digest small invertebrate animals.

The pitchers can vary in shape even within the same species of plant depending on the age of the plant, the amount of light, and whether the pitcher is growing near the ground or high up. The pitchers are filled with acidic digestive liquids. The pitchers are able to break down and absorb nutrients from animals, usually invertebrates such as insects, that fall into the pitchers. The pitchers are covered by small lids as they grow, in order to prevent the digestive liquid from being diluted by rainwater. The lids shrivel or open up when the pitchers are fully developed.

Conservation Connection

There are estimated to be approximately 76 species of Nepenthes in the world. All species of Nepenthes are listed on Appendix II to the Convention on International Trade of Endangered Species of Flora and Fauna (CITES), which restricts trade of these plants. The World Conservation Union (IUCN) lists three species of Nepenthes, all native to Borneo, as endangered. Tropical pitcher plants suffer mainly from habitat destruction, but due to the low numbers of their populations, collecting has also had serious impacts. The incidence of illegal trade in Nepenthes is high. Methods have been developed to produce Nepenthes plants from tissue culture. The horticultural use of plants produced by this process can help reduce the impact on wild Nepenthes. Woodland Park Zoo displays species of Nepenthes in the canopy dome of the Tropical Rain Forest. However, these plants produce pitchers only occasionally depending on seasonal variations of the weather.

How You Can Help!

Learn ways you can help conserve wildlife and the habitats they require for survival by visiting our How You Can Help section.

Pitcher Plants Fascinating Facts

Thirty out of the 76 known species of tropical pitcher plants occur on the island of Borneo
The brims of tropical pitcher plants secrete insect-attracting nectar. Insects are also attracted to pitcher plants by aromas and visual signals. When insects land on the brim of a pitcher and walk around in the process of foraging, they often walk over the waxy, slippery surface of the inside of the pitcher and lose their footing. The insects then fall into the pitcher and become food for the plant
Species of Nepenthes grow on soils that are poor in nutrients or on other plants where nutrients are not readily available. Plants, such as some Nepenthes, that grow on other plants, but do not take nutrients from the supporting plants, are referred to as epiphytes. In order to grow in places that are poor in nutrients, Nepenthes have adapted a carnivorous lifestyle, which supplements their intake of nitrogen and other nutrients
Most species of Nepenthes have symbiotic relationships with arthropods such as ants or spiders. One example is Nepenthes bicalcarata and ants of the genus Colobopsis in forests of Borneo. The pitcher plant provides the ants with shelter inside the tendril connecting the pitcher to the leaf. The ants collect insects that have fallen into the pitcher and feed on them. The pitcher plant gets sufficient nutrients from the insects in the pitcher, yet the ants prevent insects from piling up in the pitcher and decomposing, which can be detrimental to the plant.
Nepenthes rajah produces the largest pitchers of any plants in this genus. Pitchers of this plant are shaped somewhat like kettledrums, the largest pitchers being up to 14 inches (35 cm) long by 7 inches (18 cm) wide.

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