Summary: TRAPPED! Carnivorous Pitcher Plant Lid Closes on Prey! REPLAY Episode 18 by Niki Wilson (Click here to directly access the MP3) Nepenthes is a genus of carnivorous pitcher plants that use special leaves to capture prey. These extraordinary leaves are, as the name suggests, pitcher-shaped, and partially filled with a sticky, syrup-like digestive fluid. Insects fall inside and can’t escape due to a slippery, waxy substance that lines the inner walls and rim of the pitcher. Hovering over the rim is a lid that protects the pitcher from being flooded by rain. But for the species Nepenthes gracilis, a recent study has discovered that the lid is much, much more. In this species of pitcher plants, the lid acts as another trapping mechanism, allowing the plant to catch insects in varied weather conditions. N. gracilis is different from others in it’s genus because like the inside of the pitcher, the underside of its lid is also lined with a waxy surface. This surface less slippery than the inside walls, and allows insects to walk around on it and feed on nectar under dry conditions. Increased nectar secretions make the lower lid more attractive, and insects hang out there longer. But the lid is a false safe haven. Researchers have found that the impact of heavy raindrops caused insects like ants to fall from the lower lid surface into the pitcher. The presence of the waxy surface appears to cause the insects to detach more easily with sudden impact. In essence, a flick of the lid helped ensure the plant’s next meal. Results of the study suggest that N. gracilis has evolved special morphological adaptations to capture prey with their pitcher lid. These discoveries highlight why pitcher plants have recently emerged as what researchers describe as “a model system for studying the evolution of functional traits in plants.” Little Shop of Horrors? Probably not. But these plants once again demonstrate the power and ingenuity of evolution. Listen to the Podcast for more… Research article on this subject: With a Flick of the Lid: A Novel Trapping Mechanism in Nepenthes gracilis Pitcher Plants Niki Wilson is a science writer living in Jasper. She hails from an environmental science and biology background, but traded the field for the computer screen. She writes a regular column, On Science, for the Jasper Fitzhugh, and podcasts for Parks Canada and Experimental. She has freelanced for the Canadian Science Media Center, and is an affiliate of the Banff Centre Science Communications Program. See more of her writing at www.nikiwilson.com.
