Friday, December 7, 2012

Versatile Pitcher Plants

Pitcher Plants- Wikimedia
Pitcher plants are pretty incredible.  They are carniverous just like venus flytraps and Audry in Little Shop of Horrors.  Their long tubular leaves shaped like a test tube and produce an enticing liquid nectar at the bottom of the cup.  There is a curved lid-like structure  covering the tube to prevent rain from diluting the nectar.  Insects are drawn to the slippery rim and fall in, only to drown and then be digested by bacteria in the plant's juices or by mutualistic insect larvae living there.

That was the story when I was in school, enough to excite a young boy to having fantasies of dropping ants in and hearing their tiny screams.  Now several new findings- stranger than fiction- show just how versatile these plants can be.

A report in Natural History Magazine describes a species named Nepenthes gracilis which has an important modification.  The underside of the lid is coated with particles that allow an insect to crawl on it.  When rain hits the lid, it loses its grip and takes the fatal plunge.

Even more incredible is a report from of a species of giant mountain pitcher plants (Nepenthes rajah) of Borneo.  In a territory notably devoid of restroom facilities, it has filled a niche by becoming a toilet for shrews and rats.  

The underside of its curved lid produces an enticing nectar which the tree shrews (Tupaia montana) and summit rats (Rattus baluensis) lick up while standing over the open tubular leaf.  As mammals are wont to do, they occasionally defecate as they eat, their feces dropping to the bottom of the pitcher plant.  

Researchers set up cameras on selected pitcher plants and recorded the mammals' toilet activities.  They also collected droppings for 61 days.  (What the researchers told their children that they did for a living isn't recorded.)

The plants received their fecal snack on an average of every 3.4 days.  The nitrogen-rich feces provides the plant the nutrition it requires because of the otherwise nutrient-poor, acidic soils .  
"To learn how the pitchers attract rats and shrews, the researchers analyzed the milky substance secreted by pitcher lids. The team found more than 40 aromatic chemicals, including some commonly found in fruit—the mammals’ usual fare."
Apparently the mammals are conned into licking the chemicals without getting nutritional value.  But hey, where else can you find a clean restroom in the jungle?

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