Introduction and Background
The tiny sentry milk-vetch plant (Astragalus cremnophylax var. cremnophylax) is federally listed as an endangered species and is endemic to Grand Canyon National Park. Displaying lavender blooms in the spring and fall, this perennial herb forms a one inch tall by eight inch wide mat in pockets of shallow soil on the Kaibab limestone. Growing only within 25 feet of the canyon rim, this tiny plant overlooks the canyon, earning its name, “sentry”. Since 2006, when the Sentry Milk-Vetch Recovery Plan was completed in accordance with the Endangered Species Act, Grand Canyon National Park has partnered with the U.S. Fish and Wildlife Service, the Arboretum at Flagstaff, and the Grand Canyon Association to reverse the decline of this species.