Publication: Taxon. 31: 125. 1982.
selected vouchers: WTU
Notes: FNA7: "Though often treated as a variety of Arabis (Boechera) holboellii (e.g., R. C. Rollins 1993; G. A. Mulligan 1996; N. H. Holmgren 2005b), B. retrofracta is easily distinguished from that species by having narrower (0.9-1.8 versus 2-2.5 mm), mostly non-secund fruits that are almost always appressed to rachises. The two taxa have allopatric distributions, with B. retrofracta found on the North American continent (mostly west of the Great Plains) and B. holboellii apparently confined to Greenland. Boechera retrofracta has formed hybrids with at least 12 other species. Besides differing in macromorphological characters, all those hybrids are distinct from B. retrofracta in the strict sense in having wider (20-30 versus 13-16 Âµm), spheroid pollen grains with asymmetric colpi.
Arabis kochii Blankinship is an illegitimate name, sometimes found in synonymy with Boechera retrofracta."