McLEOD (AP) - Someone has been trying to kill western prairie fringed orchids, apparently under the mistaken belief that the protected prairie plant would restrict land use, officials say.

About 25 orchids were sprayed with herbicide in Ransom County just west of McLeod, along a trail taken by an all-terrain vehicle for 134 feet. Photographs of the sabotaged plants show drooping orchid blossoms beginning to wilt.

"You can tell they're on the way out," said Jeff Towner, a supervisor with the U.S. Fish and Wildlife Service in Bismarck. The agency enforces federal laws protecting endangered plant and animal species.

State and federal officials say it appears the spraying was deliberately aimed at a plant that is classified as threatened because of its diminishing grasslands habitat.

The orchids cannot be removed or damaged on public land, but they are not immune from disturbance on private land, said Kathy Duttenhefner, a biologist and coordinator of the North Dakota Parks and Recreation's natural resource division. The division monitors the plants for the federal government.

"The government can't come in and say, 'You can't mow this, you can't graze it,'" she said. Whoever sprayed the plants, she said, was "just afraid of the unknown, maybe of what would happen if you have a protected orchid."

The spraying was discovered in July by a parks and recreation biologist during routine monitoring. The sprayed plants were next to one of the survey plots.

Towner said whoever destroyed the plants likely will not be prosecuted, but officials want to avoid more damage.

"When it involves a plant on private land, the law applies to plants differently than it does to animals," he said. "On private land, they (plants) don't have as much protection."

Officials have not found the person responsible for the orchid spraying, Towner said Monday.

"Our special agent is going to talk with the landowner as well as neighboring landowners and try to emphasize why wanton spraying of a protected species should not be done," he said.

"Our ultimate goal for threatened and endangered species is to take them off the list," Towner said. "We can only take them off the list once they become more numerous and more stable."

The Sheyenne National Grasslands in Ransom County are known for one of the largest populations of western fringed prairie orchids, with about 3,000, according to NatureServe Explorer, an online species database. The prairie orchid's population in North Dakota since monitoring began more than 25 years ago has been relatively stable, Towner said.

In North America, the orchid is found in 172 places, mostly in the central Plains states.