By Jan TenBruggencate
Advertiser Columnist

Some folks argue that a weed is just a plant growing out of place.

If you were collecting the lawn weed known in Hawaiian as laukahi, a plantago, and you planned to use it medicinally, you'd hardly consider it a weed. Laukahi is sometimes used in traditional medicine to treat wounds, and one surfer recently told me she uses it on coral cuts after softening the leaf over a flame.

Corn is a weed if it's growing in your cabbage patch.

Some species become weeds when they are moved from their natural habitat, where they live with a host of diseases, pests and predators that limit their profusion. Move them to a place where none of these exists, and they can take off.

It can happen with plants, like miconia and black wattle in the forested areas of Hawai'i, and with insects, like the two-spotted leafhopper and mosquitoes.

It can happen with amphibians, like the noisy coqui frog, Eleutherodactylus coqui.

Coqui may have arrived in the Islands as hitchhikers on imported landscape plants, and they have spread, in part, from Hawai'i nurseries, traveling with potted plants that are carried to new sites for planting.

The animals are tiny. An adult easily fits on top of a quarter. But they have huge voices.

One resident of Lawa'i, Kaua'i, recalls that for months she fell asleep to the call of a single coqui and enjoyed it — until it apparently found a mate. Soon the woods were filled with the din of dozens of frogs. State and federal officials, working with volunteers, are trying to control that comparatively limited population before it spreads further.

Researchers are working on ways to control them in larger populations, too, but in parts of the Big Island and Maui, it may be too late. They're so widespread, they won't be controlled with known techniques. And they're still spreading fast.

In their home terrain in the Caribbean, many of the coqui's cousins are beloved and increasingly rare. Three species are believed extinct.

The Associated Press recently reported that two groups, the Center for Biological Diversity and the Puerto Rican Maunabo Development Committee, have sued the U.S. Fish and Wildlife Service for not acting aggressively enough to protect the threatened rock coqui, Eleutherodactylus cooki. Another cousin, the golden coqui or Eleutherodactylus jasperi, is also a federally listed threatened species.

The coqui is a symbol of Puerto Rico and a pest in Hawai'i, which has no native land amphibians.

Embraced in one place. A pest in another.

Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. Reach him at (808) 245-3074 or e-mail jant@honoluluadvertiser.com.