Nepenthes

Nepenthes are tropical pitcher plants, also called monkey cups. These carnivorous plants catch insects and other small animals in hanging, cup-shaped traps called pitchers, and there are more than 150 known species.

Tropical pitcher plant Quick Facts

Common name	Tropical pitcher plant
Scientific name	Nepenthes
Kingdom	Plantae
Phylum	Tracheophyta
Class	Magnoliopsida
Order	Caryophyllales
Family	Nepenthaceae
Type	Carnivorous climbing pitcher plant, called monkey cups
Diet	Carnivore: insects trapped in pitchers
Habitat	Lowland and highland tropics, split at about 1,200 m
Native range	Southeast Asia, China, India, Madagascar, northern Australia
Size	Stems up to 15 m long, 1 cm thick
Special feature	Slippery lip (peristome) makes prey fall in

Most Nepenthes grow in Southeast Asia, especially on the islands of Borneo and Sumatra and in Malaysia, Indonesia and the Philippines. A few species are found farther away, in southern China, India, Sri Lanka, northern Australia, New Caledonia, the Seychelles and Madagascar. The nickname “monkey cups” comes from stories of monkeys drinking rainwater from the pitchers.

Highland and Lowland Types

Growers and scientists often sort Nepenthes into two groups based on where they grow. Lowland species live in hot, steamy forests close to sea level. Highland species grow in cool, misty mountain forests, roughly above 1,000 to 1,200 m (3,300 to 3,900 feet). This difference matters a lot if you want to grow them at home.

Anatomy

Most Nepenthes have shallow roots and long, thin stems that either creep along the ground or climb up trees and shrubs. The stems are usually no thicker than a pencil, but climbing species can scramble 15 m (50 feet) or more up into the forest canopy.

The long, narrow leaves grow one at a time along the stem. Here is the clever part: the central vein of each leaf keeps growing past the leaf tip as a thin tendril. In many species the tendril curls around branches to help the plant climb. At the end of the tendril, a tiny bud swells and slowly grows into a pitcher shaped like a cup, tube or round jar.

Many species make two kinds of pitchers: chunky lower pitchers that sit on the ground, and slimmer upper pitchers that hang from the climbing stems. Some pitchers are tiny, but the biggest species have pitchers large enough to hold more than a liter of fluid.

How the Trap Works

A pitcher is a pitfall trap, a bit like a slippery well:

• The lure: the rim of the pitcher, called the peristome, is often brightly colored and covered with nectar. Insects such as ants and flies come to feed.
• The slip: when the peristome is wet from rain or humidity, it becomes incredibly slippery. Insects lose their footing and slide in. The waxy inside walls make climbing back out almost impossible.
• The lid: a lid above the opening has nectar glands on its underside to attract prey. In many species it also helps stop heavy rain from overflowing the pitcher and watering down the fluid inside.
• The pool: at the bottom is a pool of fluid where trapped prey drowns.

Digestion of Prey

The pitcher fluid is made by the plant. In many species it is thick and slightly sticky, which makes it harder for insects to swim out. Glands in the lower part of the pitcher release digestive enzymes that break the prey down, and the same area then soaks up the nutrients, especially nitrogen and phosphorus.

Nepenthes grow in poor, soggy or rocky soils with few nutrients, so catching animals gives them the extra food they need. A few giant mountain species from Borneo have even found a different trick: their pitchers attract tree shrews, which lick sweet nectar from the lid and leave their droppings in the pitcher as fertilizer.

Tips for Growing Nepenthes

Nepenthes are among the easier carnivorous plants to grow indoors, especially lowland hybrids sold in garden centers. Here are the basics.

Containers

A pot of about 4 liters (1 gallon) is fine for small plants, while large species may need a container of 15 to 20 liters (4 to 5 gallons). Plastic pots and hanging baskets both work. Make sure there are plenty of drainage holes so water runs out quickly and the roots get air.

Potting Mix

Use an airy, low-nutrient mix that holds moisture but drains well, such as long-fibered sphagnum moss, or a blend of peat or sphagnum with orchid bark and perlite. Never use ordinary potting compost with fertilizer in it, as it can burn the roots.

Light

Nepenthes like bright light. A few hours of gentle direct sun, ideally in the morning, or bright filtered light through a 30 to 50 percent shade cloth works well. Good light helps the plants grow strongly, brings out bright pitcher colors and can encourage flowering. Harsh midday sun can scorch the leaves.

Watering and Humidity

Keep the potting mix moist but not waterlogged, and never let it dry out completely. Use rainwater, distilled water or reverse-osmosis water, because minerals in tap water can build up and harm the roots. Most Nepenthes also need fairly high humidity to keep making new pitchers.

Temperature

Grow highland and lowland types under different conditions. Lowland species want warm days and warm nights all year. Highland species like mild days and a noticeable drop in temperature at night, similar to their cool mountain homes.

Pruning

Most Nepenthes eventually grow into long vines. Trimming back long stems now and then keeps the plant compact and encourages new shoots, which usually produce fresh pitchers.

Tropical pitcher plant FAQs

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