Flora of North America species comparison

Varieties 3 (3 in the flora).

Potentilla concinna is a relatively widespread, low-growing, early-blooming species with palmate to subpalmate, abaxially cottony leaves. Flowers often appear before leaves are fully expanded. The three varieties treated here have some level of biogeographic identity and are, therefore, given provisional taxonomic recognition. Some treatments have also included P. bicrenata, P. johnstonii, and P. macounii as varieties of P. concinna. Two Mexican species, P. leonina Standley and P. oblanceolata Rydberg, have also been treated as varieties of P. concinna by J. Soják (2006); they are retained as distinct species here, pending further research on Mexican Potentilla. Two other erstwhile varieties of P. concinna are now placed in separate sections: var. modesta (Rydberg) S. L. Welsh & B. C. Johnston (misapplied) in sect. Rubricaules as P. modesta, and var. rubripes (Rydberg) C. L. Hitchcock in sect. Subjugae, intermediate between P. saximontana and P. subjuga. Potentilla concinnaeformis Rydberg, considered to be a close relative of P. concinna by I. W. Clokey (1939), is more likely a hybrid between P. glaucophylla (sect. Graciles) and P. hippiana (sect. Leucophyllae). Hybrids also occur with P. multisecta, and probably other species as well.

Potentilla concinna was first described in 1818 as P. humifusa Nuttall, a later homonym for P. humifusa Willdenow.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

The present circumscription of Potentilla drummondii differs from that of B. Ertter (1992, 1993), which encompassed P. breweri and P. bruceae as varieties (see 28. P. bruceae discussion for details). The description above focuses on large, eglandular, subpinnate plants that occur in mountains from the central Sierra Nevada and northern Coast Ranges of California to the Olympic Peninsula of Washington, east to southern Alberta. At least some collections previously identified as P. glaucophylla (as P. diversifolia Lehmann) from the Kenai Peninsula in Alaska can be readily accommodated within this concept, as can collections from the Cabinet Mountains in Montana. The distinction between P. drummondii and subpalmate P. glaucophylla can be vague; in general, the proximalmost leaflets of P. glaucophylla are relatively small and often entire; in P. drummondii proximalmost leaflets are similar in size and dissection to other leaflets.

Pinnate-leaved regional variants merit further attention; in particular the smaller form described as Potentilla cascadensis, and glandular plants in the northern Coast Ranges of California. Relatively small plants forming uniform populations in the southern Sierra Nevada may represent stabilized hybrids with P. breweri.

The inclusion of Potentilla bruceae and P. drummondii in sect. Graciles differs from that of J. Clausen et al. (1940) and B. C. Johnston (1980, 1985), who allied both species with P. breweri in sect. Multijugae. Although subpalmate to subpinnate leaves are anomalous in primarily palmate sect. Graciles, doubled proximal leaflets and an indistinct transition between the rachis and axis of the pinnatisect terminal leaflet in these two species suggest that this state is derived from a palmate progenitor. Habit and petioles also are more compatible with sect. Graciles than sect. Multijugae.

(Discussion copyrighted by Flora of North America; reprinted with permission.)