His patent suspended by the U.S. government, a California businessman says he is giving up his rights to a rainforest plant that Amazon Indians have used for generations.

Loren Miller, a Menlo Park resident, says he hasn’t managed to find a commercial use for the plant since he received a patent from the U.S. government in 1986.

This month, the U.S. Patent and Trademark Office (USPTO) suspended Miller’s patent on a variety of Banisteriopsis caapi that he had dubbed “Da Vine.”

The move is drawing applause from environmental and indigenous-rights advocates who campaigned for revocation of the patent, arguing it is an essential part of Amazon people’s cultural heritage.

Miller, founder of a California company called International Plant Medicine Corp., pronounces himself puzzled by the commotion.

“The patent is of no use to us,” Miller says. “This patent has been sitting in a drawer since 1986, never used, harming no one. Why it became an issue 10 years later is a mystery to me.”

The plant is found in the Amazon rainforest and used by indigenous people in Ecuador, Peru, Colombia and Brazil to make a mind-altering drink for religious and healing ceremonies known as ayahuasca, or “vine of the dead.”

The patent office ruled that it would revoke Miller’s patent permanently if he fails to present additional evidence supporting his case within six months. It is against this backdrop that Miller says he has decided against fighting to retain his patent.

U.S. and South American environmental and indigenous groups have been campaigning against the patent for the past three years, claiming the plant has cultural and religious value and should not be owned by anyone.

“This is a huge deal,” says David Rothschild, a spokesman for the Coalition for Amazonian Peoples and their Environment in Washington, D.C. “This plant is a major part of their religion, their spiritual life. When they first heard that someone had a patent out… To them, it was an incredible offense.”

According to local custom, the plant gives shamans the power to cure the sick, summon spirits and predict the future. It is known as yagé, and its hallucinogenic powers were described by beat-generation writers Allen Ginsberg and William Burroughs in the 1971 book “The Yage Letters.”

Miller says he found out about the plant in 1974 and received it from someone who was cultivating it. He declines to discuss the activity and status of International Plant Medicine Corp., but claims it helped contribute to land-conservation efforts in an area of Ecuador that is home to three indigenous tribes.

“Saving the Amazon and helping the human rights of the indigenous people has always been our mission,” he says.

Yet Miller adds he has been unable to find a commercial or medicinal use for the plant.

“It has no proven medical use, it is very toxic and has high potential for abuse,” he says. “It seems to be a favorite of new-age hippies in their hallucinogenic cocktails.”

In his patent application in 1986, Miller said he discovered a novel strain of the vine. However this month’s patent-office decision states the same plant had been described in publications more than a year before he applied for the patent.

The Center for International Environmental Law in Washington, D.C., and two Amazon advocacy groups challenged the patent, saying the law under which it was granted is flawed.

“The USPTO needs to change its rules to prevent future patent claims based on the traditional knowledge and use of a plant by indigenous peoples,” David Downes, a lawyer for the groups, said in a prepared statement.

It’s unclear, however, whether such change is now in the offing. Rochelle Dreyfuss, a law professor at New York University and an expert on intellectual property rights, says the patent office decision emphasizes the protection of past research more than the defense of cultural or religious customs.

“The sacredness of the plant is not its determining feature,” Dreyfuss says. “The question is whether the plant was known or used in the United States or in the world before the application was made. I don’t think that someone with cultural feeling about the plant is going to matter.”

Nonetheless, Amazon-area indigenous groups say they are pleased with the ruling. “Our shamans and elders were very worried about this patent,” says Antonio Jacanamijoy, general coordinator of the Organization of Amazon Basin Indigenous People in Quito, Ecuador. “Now they will celebrate.”