The Interior Department is coming to the defense of the furbish lousewort, an obscure Maine snapdragon endangered by the proposed $1.3 billion Dickey-Lincoln hydroelectric project.

It will be among the first 14 plants (including the hairy rattleweed and the Santa Barbara Island liveforever) formally listed by the department as "endangered and threatened species." This would give them federal protection form the public works bulldozer.

The lousewort was thought to be extinct until about 200 specimens were discovered last year along a bank of the St. John River, which would by flooded by Dickey-Lincoln.

Unless the two-foot high lousewort can be replanted elsewhere - an unlikely event because of its complicated root system - or other specimens are discovered, the project could not be built, according to the Army Corps of Engineers.

Interior Department officials said yesterday the 14 plants, among 1,700 proposed for listing last June, will be given "endangered and threatened" status in two to four weeks.

The endangered species act, under which 637 animal, insects, fishes and reptiles have been listed as endangered or threatened, forbids federal agencies to fund or carry out any action that would jeopardize the existence of a listed species.

The listing of the furbish lousewort is expected to aggravate growing controversy over the act. It has been used by environmentalists as a tool to fight such projects as the Tellico dam on the Tennessee River, which would kill an endangered fish called the snail darter.

A bill pending in Congress would require environmental impact statements for critical habitats - areas set aside to protect threatened species - a move that could delay the listing program. Other bills would exempt various dams.

Interior Department officials acknowledged that there is public skepticism over whether the government should protect plants. "Its esoteric to some people," said Roger McManus, a department botanist. "If it doesn't have four hooves and horns and snarling teeth, it usually doesn't get much reaction."

Although the endangered plants have no apparent economic value, McManus said, "We should take great care before we eliminate whole species. Once they are gone, you can't say 'Whoops, I wish we had them back.'

"Our society is built on plants that produce clothing, food, medicine. It's difficult to say what potential use a species might have. We haven't begun to tap the biological and chemical knowledge harbored in these critters."

Quinine, for example, is produced from a South American plant, and euphorbia, a type of milkweed, contains hydrocarbons that might produce energy, McManus said.

The 14 plants to be listed next months include two threatened species - a designation somewhat less critical than endangered: the perycberg milkvetch, a trailing pea plant, and the northern wild monkshead, a blue wildflower.

The monkshead, of which about 2,000 specimens remain, is threatened by the Lafarge Dam in Wisconsin, a project President Carter wants to halt. the milkvetch is confined to two acres in Utah.

The endangered plants to be listed include the Virginia roundleaf birch tree, of which only 30 known specimens survive in a Smyth County forest; the Texas wildrice, an aquatic grass; and two Georgia plants the hairy rattleweed, an herb, and the persistent trillium, a lily.

Also five California plants - the Eureka evening primrose, the Antioch Dunes evening primrose, the Eureka dunegrass, the Contracostal wallflower and the liveforever, a small succulent on Santa Barbara Island - and two Hawaiian species the Kupao sunflower tree and the wild broadbeam flower.

Interior plans to list several hundred plant species a year, a complicated process that requires field surveys and outside botantists' review.