Convergence - the Albany Pitcher Plant

I've always been fascinated by evolutionary convergence, the phenomenon whereby distantly related species, responding to similar selective pressures, evolve similar or even identical solutions to the same problem.

In swamps around Albany, where the nutrient levels are very low, the Albany pitcher plant Cephalotus follicularis has come up with the ingenious solution to its nutrition problems of developing pitchers in which it traps insects that then supplement the meagre supply it gets from the soil. But, of course, you've heard this story before. In South East Asia, members of the genus Nepenthes have done exactly the same thing, as have Sarracenia the trumpet pitchers in the Americas.

Cephalotus follicularis is the sole species in its family Cephalotaceae confined to the south coast of Western Australia. Its closest relatives are apparently members of the Saxifrage family Saxifragaceae and so it has evolved insect trapping pitchers completely independently of Nepenthes and Sarracenia. Some of the features of such plants are obvious design features, the swollen receptacle for the digestive fluids with the lid to keep out the rain. But other features are not quite so obvious.

The margins of the pitcher in Cephalotus follicularis are strongly ribbed. Presumably this plays some role in for the same design reappears in some members of Nepenthes.

Nepenthes villosa another narrowly restricted species, endemic to the upper slopes of Mount Kinabalu on the island of Borneo. Althogh found in a completely different habitat to the Albany Pitcher Plant, this species has found a similar insect trapping solution, even down to the use of a strongly ribbed margin on its pitchers.

Comments

[Teresa Gilman]

Are you kidding? These are real plants?! Not just stuff you rigged up for Hallowe'en?

Fascinating and beautiful. And so practical, despite how they look.

Teresa

[Philip Gleeson]

Um, yes, they're real, although I should point out that the Albany pitchers are barely as big as your thumb, so they might not be attention grabbing enough for Halloween.