Fleak and Dunn (1971) placed Lupinus aquilinus, which is also endemic to the Sacramento Mountains, as a subspecies of L. sierrae-blancae noting that ssp. aquilinus differs from ssp. sierrae-blancae by its shorter racemes, on average smaller narrower leaflets, and slightly different habitat preference. Isely (1998) questioned the placement of L. aquilinus in L. sierrae-blancae, suggesting instead that it could be an inconspicuously pubescent form of L. argenteus var. argenteus, a common northern taxon. Nevertheless, he included the ssp. aquilinus as a synonym within L. sierrae-blancae.