It's an unassuming cactus – with an outsized cultural impact. From its home range in the Texas-Mexico borderlands, it's been incorporated into the religious lives of Native peoples across North America.

Peyote has mind-altering effects. It's been an illegal narcotic under U.S. law since 1965. But there's legal protection for Native use. Hundreds of thousands of indigenous people participate in peyote rituals. For those practitioners, the cactus is a sacrament, and a living bond with the ancestral past.

Alpine's Megan Wilde explores this tradition – and the existential threats it faces – in a new film, “Peyote at a Crossroads.”

Peyote has a deep history in the Texas borderl...