Single Record

PhotoRecords: YES Richard Haswell: Costilla Co, between San Luis and the Rio Grande 21 June 2023

Comments: Of silky milkvetch, there are only three confirmed Watershed records, all recent and all from Costilla Co roughly within a ten miles radius of Jaroso, on “alluvial flats” and “rocky bare sandstone hills” (Kelaidis and Kelaidis 1990; Islam 2014; and Haswell 2023, a photorecord. A fourth observation is inferred, a voucher collected by Kelaidis and Kelaidis on the same day in 1990 "between Jaroso and Antonito" but determined as "Astragalus aretioides." Distinction between A. aretioides and A. sericoleucus depends on close examination of the stipules, which are not easy to see in this mat-forming plant. Since the closest USA observations of A. aretioides are the extreme northwest and northeast corners of Colorado, it is assumed that the specimen in question is A. sericoleucus. Note that the specimen identified by Kelaidis and Kelaidis as "Astragalus sericoleucus" is located "between Jaroso and the Rio Grande" whereas the geocoordinates that they give point to 4.4 miles north of San Luis. The USA distribution of A. sericoleucus is the southern half of Wyoming, contingent parts of northeast Colorado, then these isolated locations in the Watershed on down through the top fourth of New Mexico (on "prairies, grassy plains, hills, knolls," Allred et al., 2022) but no farther down the Rio Grande drainage. Note that one defining character of A. sericoleucus is the minute seed (2 mm wide, 3-5 mm long).