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Pitcher plants

06/19/07 12:00AM By Ruth Page
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(HOST) At a time of year when many of us are already busy tending transplants and seedlings, commentator Ruth Page is thinking about plants that are not your average garden-variety.

(PAGE) Animals eating plants, as we do, seems to fit the normal order of things. But for plants to eat animals defies reason. We all know, though, that some do. Sundews lure insects by their attractive odor, then snap their spiky sides shut to trap them; enzymes in the plants' juices help digest the prey, giving the plants protein. Pitcher plants are usually shaped like narrow, deep bowls; when an insect lands on one of these, it slides down to the bottom and can't climb the slippery sides to get out.

Pitcher plants in other parts of the world have a lot more variety. Most pitcher plants don't offer enough liquid to reward a hungry hiker in this country. But in some arid areas of the world, a hiker might sip from one species of Nepenthes that offers a half-pint of sweet liquid; take a look; nothing in there? Safe to drink. The largest of those grow on a mountain in Borneo. Such pitchers can grow a foot long.

Our familiar pitchers grow up from the ground; there's a species in some countries that has to climb on supports, hanging its dangling pitchers down.

Some pitchers attract insects just as flowers do, by scent, color, and a sweet reward. For a flower, that just means it gets pollinated; for the pitcher plant, it means it gets dinner. The rafflesiana species grows in both aerial and terrestrial forms. They can trap not only tiny ants, but even beetles.

There's a pitcher plant in Borneo that prefers to dine on termites. The plants have a hairy band of white around their necks just at the upper, outer edge of the pitcher. Some termites feed on lichens that look just like that. They're attracted to the white neckties on the pitchers in droves, and some inevitably fall into the open pitcher.

There are tiny animals, probably tree shrews, that have dainty bathroom habits. They use a species of Nepenthes that makes little bowls, like little toilets. The pitcher plants get nutrients from those deliveries. Some pitchers are vegetarian: walk through woodlands from New Guinea to Thailand, and you may see what look like several dozen little teacups sitting on the forest floor. Those open, green-edged cups are waiting for plant leaves and flowers to fall from above and feed them.

Mites, midges, mosquitoes and ants have all been found living inside a pitcher, in apparent safety. Some ants reside inside round tendrils connecting a pitcher to its leaf. This pitcher actually feeds the ants with nectar from little thorns that project over the pitcher's mouth. Nectar is only part of the ant diet; when the ants eat a large insect at the edge of the pitcher, bits and pieces fall in, and feed the plant.

Nature believes in variety.

Ruth Page has been following environmental issues for twenty years. She is a long time Vermont resident and currently lives in Shelburne.

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