Discover, December 1992
Plants - Oh, Wilbur
Stipa robusta, "Sleepy Grass" to its friends, is a tough plant. Not only does it survive in the rugged terrain of the southwestern Rocky Mountains, but it has also evolved a unique defense against animals that graze on its feathery plumes. It harbors a fungus called Acremonium, which produces a powerful poison that can knock a horse cold for up to a week. The fungus gets passed on to future generations through the plant's seeds. "The fungus gets a home and gets fed, and the grass gets protection from critters that want to eat it," says Indiana University biologist Keith Clay. "So it's a mutually beneficial association, not a disease." In pastures where every other type of vegetation has been nibbled to the ground, one can easily spot the sleepy grass - tall, proud, and untouched.
Clay and his co-workers Richard Petroski and Richard Powell from the US Department of Agriculture have now isolated the chemical that gives the sleepy grass fungus its potent punch. It is an alkaloid called lysergic acid amide. Alkaloids are the poisons in hundreds of poisonous plants, and lysergic acid amide has been found before in a few of them, but never in such high concentrations as in sleepy grass.
Lysergic acid amide is a potent sedative in humans as well; Central American Indians are said to quiet crying infants by feeding them a single sleepy-grass seed. In fact, in the 1950s American pharmaceutical manufacturers (who didn't know about the sleepy grass connection) considered marketing the compound as a prescription sleeping aid. Bu the idea ran aground on a public relations problem. Lysergic Acid amide has a close chemical relative called lysergic acid diethylamide, which is more commonly known as LSD. "When the pharmaceutical industry discovered the compound's link to LSD and all the problems associated with that," says Clay, "they essentially dropped it."