One of the world's rarest flowering plants, the autumn buttercup - found only in an area about the size of two or three desk tops in western Garfield County - may soon be protected as an endangered species.

Until 1982, when a botanist discovered a group of about 400 of them, the autumn buttercup was believed to be extinct.Officials of the U.S. Fish and Wildlife Service want to designate the plant as an endangered species because that would give it special protection. It grows only in a peat bog on private property about 10 miles north of Panguitch.

A Federal Register notice printed July 22 calls for public comment on the plant, which has the scientific name Ranunculus acriformis var. aestivalis. Comments are due by Sept. 20 at the agency's Salt Lake office.

According to the notice, "The single known population has experienced a population decline of over 90 percent in the past five years."

Larry England, a botanist with the Fish and Wildlife Service's Salt Lake City office, said the habitat may be similar to the way the region was during the last ice age, when the area was much wetter. So experts think the plant may be a "relic" or holdover species from the Pleistocene era.

The variety was discovered around the turn of the century by Marcus E. Jones, Utah's first great home-grown botanist.

"He didn't name it, however, and it was sent to a herbarium in California," England said. (A herbarium is a museum for pressed and dried plants.) "The specimen was rediscovered by Lyman Benson in the late 1940s." Benson realized that the specimen had been in the herbarium about 50 years and that nobody knew exactly what it was.

Benson used Jones' diary to retrace the earlier scientist's footsteps, finding the plant in the same area near the Sevier River. Benson noted its small population and precarious situation and wrote detailed directions so it could be found again.

For 35 years, experts searched for it from time to time, but the plant couldn't be located. The Fish and Wildlife Service decided in the mid-1970s that it was probably extinct.

In 1982, botanist Kathy Muntz, who was from Utah but now lives in Colorado, helped prepare a survey of scarce plants for the service. On Aug. 23, 1982, she discovered a tiny group of the plants, living some ways north of the original population. The plants Jones and Benson had found were gone, but in the other group, Muntz counted 407 adults and 64 seedlings.

Since then, the population dropped quickly, with grazing damage mostly causing the decline. "The mice are doing a number on it, meadow mice or voles," England said. In addition, the buttercup doesn't flower and reproduce some years.

"It's known from one knoll that's less than one-one hundredth of an acre," England said. "The area is about the size of two desk tops, maybe three desk tops."

Since the plant's rediscovery, the Fish and Wildlife Service has built a fence around the tiny population to protect it from cattle grazing. Property owner Douglas Evans has been cooperating with the federal experts.

"He's been helpful," England said. "He's in fact a little bit pleased with the uniqueness of the situation."

England has only seen this great rarity flower once, and that was two years ago. The flowers grow on the ends of stems two or three feet tall, and the blossoms are "about a third of an inch across, five yellow petals," he said.

In 1982, there were 407 of the plants. At the latest count, botanists found only 20.

"So the trend is not good," England said.