BILLINGS, Mont.— Conservation groups filed a petition today with the U.S. Fish and Wildlife Service to protect the thick-leaf bladderpod under the Endangered Species Act. The rare plant is found in a small area of southern Montana’s Pryor Desert, where it is supposed to be protected, but instead is under imminent threat by gypsum mining.

“This burly little plant survives in a harsh, cold desert, but it can’t survive mining,” said Tamara Strobel, a staff scientist at the Center for Biological Diversity. “Without protection under the Endangered Species Act, the thick-leaved bladderpod and its unique habitat will be lost forever.”

In 2009 the Bureau of Land Management nominated 2,606 acres as an “area of critical environmental concern” to protect the historic, archaeological and cultural values of the Gyp Springs area and the large concentration of sensitive plant species, including the bladderpod, found in the Pryor Desert. And in 2015 the agency recommended that the area be withdrawn from mineral leasing. But under the Trump administration, that did not occur.

Now the mining company Grupo Cementos de Chihuahua has plans to mine the area for gypsum, risking the survival of not only the bladderpod but also the imperiled greater sage grouse. The planned mining would also disturb Jurassic Period fossils and archaeological sites of value to the Crow and Northern Cheyenne tribes.

“The concentration of rare plants makes this a unique part of Montana,” said Peter Lesica, conservation chair of Montana Native Plant Society. “It is hard to imagine that BLM would allow mining on what they recently declared to be an ‘area of critical environmental concern.’ ”

“Rare plant species are an important example of the many natural and cultural treasures of the Pryor Mountains that need protecting,” said Dick Walton, spokesperson for the Pryors Coalition. “The Pryors are one of the Crow Tribe’s most sacred landscapes.”

The thick-leaf bladderpod is a rare, tiny, yellow-flowered plant only a few inches in size. It’s endemic to a specific substrate of reddish-pink soil made of limestone and sedimentary rock found only in a small area of the Pryor Desert.

The plant is dependent on cryptobiotic crusts, which are living soils made of blue-green algae, lichens, mosses, micro fungi and bacteria and are highly sensitive to disturbance. Once crushed by vehicles, such crusts can take hundreds of years to grow back — if at all.

Petitioners were the Center for Biological Diversity, Montana Native Plant Society and the Pryors Coalition.