Among the 1,750 species of plants at Grand Canyon, there is only one federally-listed as endangered: the sentry milkvetch (Astragalus cremnophylax var. cremnophylax). A member of the pea family, sentry milkvetch is a tiny, perennial herb that grows only in shallow soil pockets in cracks of the Kaibab Limestone, within 25 feet of the rim of Grand Canyon. Spend a Minute Out In It with the park's Vegetation crew, as they protect some of the precious few sentry milkvetch growing on the edge of the world. NPS Video/R. Lane and K. Caesar An audio-described version of the film can be found here: https://www.nps.gov/media/video/view.htm?id=4CE98ECA-C4FE-4B34-B748-9ABCCBA99341