It's a plant-eat-bug world out there

Posted: Thursday, July 03, 2003

In the corporate arena it's often a dog-eat-dog world, but in the great outdoors of the Kenai National Wildlife Refuge, at times it's more appropriate to say it's a plant-eat-bug world.

The refuge is a sanctuary for many species of flora and fauna and is home to three different types of carnivorous plants: the sundew, the bladderwort and the butterwort.

"We certainly have a lot of sundew here in the fens and muskegs," said refuge ecologist Ed Berg. "Now is a good time to look for them."

Of the three species of carnivorous plants found in the refuge, Berg said sundews are perhaps the easiest to see and identify.

This is a small, reddish-pink plant, rarely growing more than two inches tall. However, where one sundew will grow, there will often be many, so many in fact that the ground often will look like a spongy, red carpet.

Upon closer inspection of the plant, it becomes apparent how accurate the name "sundew" truly is. The plant grows narrow stems with one of two types of paddlelike leaves, depending on the species.

"There are two species of sundew here," said Berg. "Drosera rotundifolia, which has round, circular leaves, and D. anglica, which has longer, more spatula-shaped leaves."

The leaves of both species have numerous, minute hairlike appendages, often referred to as tentacles. These tentacles exude a shiny, dewlike substance (hence the name). The substance functions as an attractive nectar to insect prey and has adhesive compounds and digestive enzymes to trap the bugs as well.

This method of catching insects is referred to as adhesive trapping, and like the sundew, it is the method of choice for the butterwort.

The butterwort is slightly larger than the sundew, attaining lengths of 4 to 6 inches, but has an altogether different appearance.

The plant itself is fairly plain-looking, but will grow colorful flowers that look similar to violets. The leaves of the plant are flat and grow in dense clusters.

The name of the plant is said to be derived from the greasy, buttery, feel of the leaves which secrete a digestive mucous. Insects are attracted and become stuck in the coating, providing a nutritious meal for the butterwort.

Berg said this species is much more difficult to see than the sundew.

"I only see butterworts in the alpine areas," he said.

The third species of carnivorous plant found in the refuge is completely different from the other two in appearance, habitat and trapping method.

"Bladderworts are an aquatic plant found in many ponds here," said Berg. "They have quite an ingenious trapping system."

The clever system of catching food that Berg was referring to is known as a suction trap. The bladderwort produces numerous bladders, or balloonlike sacs, that the plant pumps water out of producing a lower pressure than outside the sac.

The sacs have an airtight trap door that grows long, sensitive, hairlike organs, which when triggered by prey, open the door to the sac. Water and the prey are subsequently sucked into the vacuum produced by the sac with lightning speed. The door snaps shut behind the prey and digestion begins.

These bladders, although numerous, are quite small. Many are only a quarter of an inch in size, so typical prey consists of insect larvae rather than the insects themselves.

For more information on carnivorous plants, visit or call the Kenai National Wildlife Refuge Headquarters and Visitor Center at 262-7021.

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