Currently there is one Federally listed endangered plant found within the boundaries of Grand Canyon National Park: the sentry milk-vetch ( Astragalus cremnophylax var. cremnophylax ). This plant is endemic to Grand Canyon and is a perennial, mat-forming herb. It grows in crevices and on rimrock in the Kaibab Limestone formation within the pinyon-juniper vegetation type. The exact location cannot be disclosed.
The name Astragalus is derived from either the Greek word meaning ankle-bone or dice, perhaps in reference to the rattling of the seed within the fruit, or it may be derived from astro meaning star and gala meaning milk, in reference to the belief that its use in pasture land improves livestock milk yield. The specific epithet cremnophylax is from the words cremno meaning gorge and phylax meaning watchman.
