The North Creek Wetland

Pitcher Plant

Tropical Pitcher Plants – Nepenthes sp.

Note: The name of this plant is Nepenthes carunculata, but the taxonomy is disputed. Some say they should be lumped under N. bongo. This article is a general overview of many tropical pitcher plants (unless otherwise noted)

Morphology / Plant Growth

Low spreading on the ground herbaceous plant, or climbing epiphyte vine (living on branches or stone walls without soil). Elaborate vase-shaped cups are made from leaf tissue and filled with water and digestive enzymes. The cups have a lid to cover the opening to prevent rain from filling the cups completely and dragging them down. The entry to the cup can be fragrant or brightly colored to attract animals and has a very slippery edge at the mouth.

These plants are considered colloquially as “carnivorous plants”. Technically, carnivores are heterotrophs (consumer of others) that eat other animals (or flesh) for energy (carbon). Calling this plant a carnivore isn’t very accurate. Notice the leaves are green? That means this plant photosynthesizes sunlight and carbon dioxide for its own sugars and energy, making it an autotroph, or producer. So why the death traps?

Pitcher plants (and other “carnivorous plants”) live in areas that are low in nutrients, especially nitrogen: like the epiphytes that don’t have soil to absorb nutrients, or the ones that grow on the ground in wetlands. These specialized leaves (death traps) will often attract insects, small animals like frogs and salamanders, and bats, with something that the animal needs or likes – like sugars or fragrance. The animal will fall in and be digested by the plant. In some cases, the animals will sleep in the pitcher plant, defecate for the plant, and the plant will absorb the nitrogen from the feces – leaving the animal unscathed, yet housed!

For N. ampullaria, the top of the pitcher lid can move. This allows the pitcher to catch leaves and debris from the sky, items high in nitrogen. The juices inside the cup will break down and absorb the nutrients from the leaves. No animals needed. Other pitcher plants have animals living in the cup, or insects breeding in the liquid and not getting trapped.

All that to say, pitcher plants really consume insects for nitrogen and other trace minerals and don’t need them for energy. You can think of it as a natural multi-vitamin to their sunlight and C02 diet.

Distribution/Habitat

Nepenthes carunculata grows in Sumatra, Indonesia. Pitcher plants grow in tropical habitats in warm locations like Australia, Madagascar, and South Pacific Islands. American pitcher plants (Sarracenia) have a different shape of pitcher, and grow in wetland areas in the eastern part of the US and Canada.

Reproduction

People are so interested in the most flashy part of the plant (the pitchers) but these also produce flowers in order to reproduce. N. carunculata is dioeceous (meaning sexes are separated). A plant is either male or female, and both are needed in order to reproduce. While these plants generally spread vegetatively, in order to produce seeds, a pollinator is needed to move the male pollen to the female flower. Imagine being that insect – visit the flowers, not the pitchers!

Human Uses

These plants are often traded illegally on the international market and sold as exotic household plants. Like elephants – this species is getting poached for money. Besides being removed from their environments, they are struggling to survive from habitat loss and development. Out of 104 Nepenthes species, 63 are on the IUCN Red list as Vunerable or Endangered, and 9 of them are Critically Endangered. Not all Nepenthes on the market are poached. Some horticulturalists are licensed to sell them and hope to conserve the species while trying to flood the market with greenhouse versions.

Resources

This article was written by Sarah Verlinde. For questions regarding the UWB/CC Plant Tour, contact Sarah at severlin@uw.edu.