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This is a habit shot of a prostrate Potentilla growing at ~8000' elevation in a sandy area within the large meadow complex known as 'Vallecitos'. It was taken during the June 2014 Jepson Workshop led by Jon Rebman. Unfortunately, I missed the name given for this...since, as often happens, I had fallen behind the group while taking photos of earlier finds.

So I consulted the 1980 'Flora of Baja California' by Ira Wiggins, and this keyed (on pg. 795) to Potentilla wheeleri var. rimicola via the following characters:

• Leaves digitately compound
• Stems decumbent to subprostrate, hirsute to glabrate, not glandular-viscid; leaves 5- to 7-foliate; leaflets 1-2 cm long; petals up to twice as long as sepals; stamens 20; grassy meadows, mountain slopes, and valleys, Sierras Juarez and San Pedro Martir; to San Jacinto Mnt., Caifornia; July-Aug.

Using the JM2 key with the photos here leads (perhaps not surprisingly) to (the nominate form of) P. wheeleri via the following couplet sequence:

      1'. Flowers in cymes; stolons 0;

      4'. Styles >= 1 mm, ± slender; petals ± obcordate, > sepals;

      12'. Leaflets > 3; inflorescence generally > 7-flowered;

      15'. Leaf palmate;

      25. Stem ± prostrate, generally <= 25 cm; pedicels generally ± recurved in fruit; leaflet teeth < 11; > 1800 m;

      26'. Leaflet surfaces ± equally strigose; s California Floristic Province;

      27.Plant rosetted to tufted in sandy soil; pistils generally > 15; fruit ± veined; pedicels generally < 15 mm; (southern Mountains)......wheeleri

The JM2 description of P. wheeleri fits this plant fairly well, as does John Game's image image here. But, interestingly, there's an ''Unabridged Note'' after the JM2 description that states:  

    ''Plants called Potentilla wheeleri in northern Baja California are Potentilla luteosericea Rydb.''

Researching this further, I found that note was backed up by both the most current plant list for the SSPM, provided to us by Jon Rebman, and a 2010 annotated plant list by Thorne, Moran & Minnich. Both lists give P. luteosericea as the current name, with P. wheeleri given as a synonym (or better, a 'replacement name', as P. wheeleri had become a homonym, i.e. it applied to more than one taxon). [Speaking of name nuances, note well that P. luteosericea of Baja California should not be confused with P. pseudosericea of (Alta) California! The latter is quite different!]

Still, I was curious as to how P. luteosericea is separated from (the current circumscription of) P. wheeleri. The checklist of Thorne et al stated it was a 'frequent and locally abundant sprawling perennial endemic on sandy meadows, 1450-2800 m', but I hoped to find more specific discriminants. In pursuing this I encountered the following four links, which helped clarify the history of the circumscriptions here:

• first a reference to P. luteosericea under the discussion of P. wheeleri in the 1925 paper 'Potentilla of southern California' by Munz & Johnston;
• second, Rydberg's original 1898 description and the holotype image here (but note that Rydberg (erroneously?) refers to the basal leaves as ''pinnate''!);
• third, the recent 2007 paper by Barbara Errter clarifying some of the U.S. taxa associated with P. wheeleri, and making mention of P. luteosericea (unfortunately excluded from her key), where it's described as having ''more open inflorescences [than P. wheeleri], leaves that are sometimes subpalmate, and less hairy leaflets that are only shallowly toothed...''; and
• fourth, the TROPICOS web page for P. luteosericea , which does not list the name as a synonym, and I take as implying current species status.

More images of Potentilla luteosericea can be found on the SDMNH photo page (search under the species name there).