Darlingtonia

In my last post (“Darlingtonia” on 06-11-2018) I described the structure of a Darlingtonia (Darlingtonia californica) plant. This carnivorous plant, which often grows on nutrient-poor substrates, has evolved its unusual form to trap insects and thus supplement its nutritional requirements.

Insects, lured by fragrant nectar, land on the plant’s “tongue” or the mustache-like appendages under the head or hood. Slanting hairs guide the insects toward an opening at the base of the hood. These slanting hairs also block the insect’s escape.

Translucent Spots

Once inside, insects try to escape by flying out of translucent spots on the top and back of the hood. These spots keep the insects away from the entrance hole. As they continuously attempt to fly out of the “false windows” the insects tire and fall into the water which fills the bottom of the hollow leaf. The walls of the plant tube are waxy and slippery and have downward pointing hairs, which prevents the insects from climbing back up the tube.

Decomposed Insects

The insects are decomposed by microorganisms in the fluid. The released nutrients are absorbed by the plant. The picture above shows a sludge of insects in the base of the Darlingtonia tube.

Darlingtonia plants do not trap rainwater. Instead the water in the base of the plant is secreted by the plant itself and the water level is kept constant by pumping water from the roots.

The cells lining the base of the hollow tube that absorb the nutrients are the same as those cells on the Darlingtonia roots that absorb nutrients from the soil.

General consensus has been that bacteria decompose the insects in the water trap and that Darlingtonia does not secrete proteolytic enzymes. However, recent studies suggest that Darlingtonia does also excrete enzymes into the water which help digest the insects.

These Darlingtonia specimens were photographed along Howland Hill Road in the Redwoods National State Parks and along Stony Creek and Myrtle Creek Trails in the Smith River National Recreation Area, all in Del Norte County CA.

The way Darlingtonia adapted to survive on nutrient-poor soils amazes me.