Subalpine slopes on Mores Mountain and Shafer Butte are often densely covered by this small-flowered representative of the silver lupine complex, especially where snowbanks persist late in the season.  In some sites, the plants are co-dominant with mountain big sagebrush (Artemisia tridentata ssp. vaseyana).  One might think that such an abundant and relatively distinctive lupine should be easily associated with one of the names currently in use, but that turns out not to be the case (as is too often true for many other populations in this exceptionally complex and perplexing genus).

The silvery leaves, relatively short inflorescences, small flowers (7–8 mm), short-bulged calyx, hairy banner back (at least below the calyx), and minimal gap between banner and wings at full anthesis make this key to L. holosericeus in Vascular Plants of the Pacific Northwest (Hitchcock et al. 1961).  This was converted into L. argenteus var. holosericeus by Barneby (1989), in “an attempt to apply to Lupinus in our region standards of specific and subordinate rank comparable to other genera of Fabaceae”.  The recent treatment of Lupinus for Flora of North America (Sholars & Riggins 2023) largely follows Barneby, at least for perennial species.  Holo lupine is the available common name for this lupine, at whatever rank.

Although the description is a reasonable fit for the subalpine lupine on the Boise Ridge, the habitat is more complicated.  The treatment of L. holosericeus in Hitchcock et al. (1961) is reasonably compatible, albeit vague: “Pine woodlands and sagebrush slopes” in the mountains of south-central Idaho and adjacent Oregon.  Barneby (1989), however, indicates that the variety is primarily known on “sagebrush plains and low hills”, mostly below 1900 meters (about 6230 feet) elevation; in contrast, our plants from the Boise Ridge are mostly above 2000 meters.  Barneby might have been focusing only on those plants occurring in the Intermountain Flora (i.e., Snake River Plains and south), since he expanded the distribution to include northern Nevada and possibly Colorado while at the same time omitting any mention of central Idaho.  This distribution is largely repeated by Sholars and Riggins (2023), with the addition of northeastern Utah.

Given that the only populations in the Boise Front coverage are subalpine, this raises the possibility that the subalpine plants are not the same as those from lower elevations.  As a further twist, the name L. holosericea is based on a collection by Thomas Nuttall in 1840, purportedly from “islands and gravelly banks” of the Willamette River in western Oregon; however, this is generally considered a mistaken locality, and more likely collected during Nuttall’s trek across southwestern Idaho.

The application of var. holosericeus to plants known in the Boise Front only from the subalpine zone is accordingly suspect, though no obvious alternative currently presents itself.

If so, it is possible that one of the nearly 600 names in synonymy

in southern Idaho that variety is primarily known from middle and lower elevations.

var. holosericeus in Flora of North America (Sholars & Riggins 2023), aka Holo lupine.  According to Barneby’s 1989 treatment for the Intermountain Flora, which Flora of North America largely follows,

Earlier treatments provide a plethora of options to choose from, though whether our subalpine plants match any of them would take significant work to determine.  According to the treatment of Lupinus in Vascular Plants of the Pacific Northwest (Hitchcock et al. 1961), “Taxonomically, the genus is probably in a more chaotic state than any other to be found in our area, nearly 600 taxa having been described for the U.S.”  The vast majority of these validly published names are currently treated as taxonomic synonyms of a much smaller number in active use, but are available for “resurrection” (yes, that is a word that taxonomists use!) if deemed appropriate.

provisional (though the same can be said for many other populations in this exceptionally complex and perplexing genus).  “Snowbank lupine” is accordingly suggested here as a common name for whatever we actually have.

Barneby. R. C.  1989.  Fabales.  Intermountain Flora, vol. 3, part B.

Hitchcock, C. L., A. Cronquist, M. Ownbey, and J. W. Thompson.  1961.  Vascular Plants of the Pacific Northwest, part 3: Saxifragaceae to Ericaceae.  University of Washington Press.

Sholars, T. and R. Riggins.  2023.  Lupinus.  Flora of North America north of Mexico 11.1: 193–249.