File:Grand Canyon sentry milk-vetch 3950 (5752390761).jpg

Grand Canyon’s rarest plant, sentry milk-vetch (Astragalus cremnophylax var. cremnophylax), grows at only three locations on the South Rim.. . This tiny member of the pea family with minute pale purple flowers favors very specific habitats at the canyon's edge. Listed as endangered in 1990, sentry milk-vetch is at risk of extinction because the plant exists in just three populations in very small numbers.. . The 2006 Sentry Milk-vetch Recovery Plan prepared by the U.S. Fish and Wildlife Service called for a number of major actions to be implemented in order to protect the species, including establishing a refuge greenhouse (ex situ) population, conducting ecological studies of the plant’s habitat requirements, surveying potential habitat to see if other populations exist, and establishing new populations to meet recovery goals.. . Read more of this Canyon Sketches article here: <a href="http://www.nps.gov/grca/naturescience/cynsk-v16.htm" rel="nofollow">www.nps.gov/grca/naturescience/cynsk-v16.htm</a>. .