WASHINGTON (AP) — The U.S. Fish and Wildlife Service will study whether a rare cactus should be protected as an endangered species, which could affect oil drilling in the Uinta Basin.

Fish and Wildlife is taking the action — the first step toward deciding whether to list the plant as protected — in response to a 2005 lawsuit by conservation groups asking for emergency help for the Pariette cactus.

The groups say a proposal to double the number of oil wells in the area where the cactus is found threaten its existence.

The Pariette was originally thought to be a form of another species, the Uinta Basin hookless cactus, which is already listed under the Endangered Species Act. But in 1996, scientists decided Pariette was a separate species.

Fish and Wildlife will officially determine whether the hookless cactus is actually three different species, including the Pariette, and whether the Pariette deserves its own Endangered Species Act protection, said Diane Katzenberger, a spokeswoman for the service.

The service should have a decision on both by the end of next year, Katzenberger said.

Advocates for the plant say the there are only about 4,000 Pariette cacti in the world, found only in a single 10-mile by 3-mile drainage in the Uinta Basin of northeastern Utah. The fragile cactus has a spiny round base and grows shiny, purple blooms.

J. Mark Porter, a research scientist and Rancho Santa Ana Botanic Garden in California, said studies have shown the cactus might not do well if transplanted somewhere else.

Erin Robertson, a staff biologist at the Center for Native Ecosystems in Denver, said the separate listing is important because it would mean the proposed impacts of activity around the plant would be evaluated on a much different scale.

Expanding drilling in a relatively small area could threaten the plant's entire population, Robertson said.

"Endangered Species Act protection is the best way to keep this beautiful wildflower from disappearing because of irresponsible drilling," she said.