Plants generate their own food via photosynthesis, so why do carnivorous plants need to catch insects? The answer is nitrogen, an element essential to produce proteins, and one that is in short supply in many of the soils where carnivorous plants live. By capturing and digesting insects and other protein-rich animals, these plants supplement their nitrogen supplies. Our bog border replicates a seep in the Klamath-Siskyou Mountains of southwestern Oregon, where cold water flows through the spongy soil, leaching nutrients. This is the home of the cobra lily (Darlingtonia californica), a unique carnivorous plant only found naturally in Oregon and California.

Photos: Darlingtonia (1 and 2), Pinguicula vulgaris

Cobra lilies capture insects using pitcher traps, formed from leaves that are rolled up into a tube. Their traps are hooded, with a forked ‘tongue’ hanging down, though this doesn’t seem to be part of the trap mechanism. Insects enter through a tiny hole and slip downwards into a liquid that contains digestive enzymes. Translucent patches in the hood act as false holes and insects that attempt to escape through them soon tire and drop to their demise. Cobra lily flowers appear in spring on long stalks held well above the traps, to prevent inadvertent capture of pollinating insects; bees seem to be the primary pollinator.

Cobra lilies are related to the pitcher plants (Sarracenia) of the Eastern Seaboard, but unlike them, they dislike warm, stagnant conditions. Their roots will die if exposed to temperatures above 50 °F and it is not uncommon to find them growing alongside streams or at seeps, where cold water flows through the soil. These habitats are home to other carnivorous plants, including butterwort (Pinguicula vulgaris) and false asphodel (Triantha occidentalis), the latter only discovered to be carnivorous in 2021.