Featured Image: Nepenthes ‘Diana’. Hybrid of ventricosa x sibuyanensis & red ampullaria (endemic to the Philippines and Borneo).
As we discuss on our Rainforest Biodiversity Page, Sumatra and Borneo’s rainforests are known to house some of the greatest diversity of carnivorous tropical pitcher plants, also known as Nepenthes.
Nepenthes can be divided into two groups: highland and lowland pitcher plants. The highland pitcher plants consist of 70% of all Nepenthes species and are found in tropical highlands and mountainous regions. They are known to grow at elevations of approximately 3,000 to 10,000 feet above sea level. Lowland Nepenthes grow below 3,000 feet sea level and are often subject to high temperatures during both day and night with high humidity.
Pitcher plants have cupped, pitcher-shaped leaves that form a deep cavity referred to as “pitfall traps”. These pitcher traps are used to lure and trap insects and other prey in their digestive liquids near the pitcher’s base. The pitcher contains a liquid, or nectar, which allows the plant to drown and dissolve the insect to be digested by the plant for energy. While pitcher plants primarily consume insects, there have also been reports of the Nepenthes rajah “eating” rodents.
While Nepenthes are carnivorous plants, they are known to have various mutually beneficial relationships with many of the local fauna. The Nepenthes rajah (left) is known to have a symbiotic relationship with tree shrews. The Nepenthes offers the tree shrews nectar that they can lick from inside the pitcher’s lid. Tree shrews are also known to use the pitchers as a “toilet” to urinate and defecate. The plant then uses the collected excrement as a source of phosphorus and nitrogen. Researchers have also found evidence of frog species with adaptive immunity to the plants’ digestive liquids, which allows them to lay eggs deep in the pitchers for their tadpoles to hatch in the pooled water source.
Along with the tree shrews and frogs, there have been instances where orangutans have utilized the unique pitcher plants to their advantage. The widest known use of these plants by orangutans is using the pitchers to drink liquids out of. You can see a video of this below.
An Infant Orangutan Drinking from a Pitcher Plant
California Carnivores. (2021). Tropical Pitcher Plants (Nepenthes). https://www.californiacarnivores.com/pages/tropical-pitcher-plants-nepenthes
Ziegler, C. (2015, January 28). The Living, Breathing World of Borneo’s Carnivorous Pitcher Plants. Photography. https://www.nationalgeographic.com/photography/proof/2015/01/28/the-living-breathing-world-of-borneos-carnivorous-pitcher-plants/