| | 1. Shrub; fruit densely hairy |
| P. fruticosa |
| | 1' Herb; fruit glabrous (often among receptacle hairs) |
| |
| | 2. Petals dark red, narrowly ovate, << sepals — plant openly matted from stolons, often floating; bogs, marshes |
| P. palustris |
| | 2' Petals yellow to white, elliptic to obcordate, < to > sepals |
| |
| | 3. Flowers solitary from stolons; leaf pinnate, main lateral leaflets alternating with reduced leaflets |
| P. anserina |
| | 4. Leaf 3–15 cm, generally densely hairy above; pedicel generally 2–7 cm; 1200–2500 m; s High Sierra Nevada, San Bernardino Mountains, Great Basin Floristic Province |
| subsp. anserina |
| | 4' Leaf 3–75 cm, ± glabrous above; pedicel generally 5–30 cm; generally < 150 m; North Coast, Central Coast, South Coast |
| subsp. pacifica |
| | 3' Flowers in cymes (stolons 0); leaf pinnate, palmate, or ternate; reduced leaflets 0 |
| |
| | 5. Styles attached below middle of fruit, widest near middle — leaf pinnate, terminal leaflet > others |
| P. glandulosa |
| | 6. Styles 1.5–2.5 mm, ± slender; flowers generally not opening fully; sheathing leaf base generally strigose |
| |
| | 7. Stem generally 5–20 cm; hairs sparse, some glandular; terminal leaflet generally 5–15 mm, < 10-toothed; San Gabriel Mountains |
| subsp. ewanii |
| | 7' Stem 20–50 cm; hairs generally ± dense, ± nonglandular; terminal leaflet generally 15–30 mm, > 10-toothed; n California |
| subsp. globosa |
| | 6' Styles generally < 1.5 mm, generally swollen; flower opening fully; sheathing leaf base often glabrous |
| |
| | 8. Petals ± elliptic-(ob)ovate; sepals ± = or > petal, generally ± obtuse; stem and pedicel hairs generally glandular; leaflet generally double-toothed; generally < 2600 m |
| |
| | 9. Petals ± elliptic-ovate, 3.5–6 mm wide, cream to pale yellow; inflorescence appearing ± leafy (bracts ± 1/2 subtended branches); generally < 1200 m |
| subsp. glandulosa |
| | 9' Petals narrowly elliptic-obovate, 2–3.5 mm wide, yellow; inflorescence not appearing very leafy (bracts < 1/2 subtended branches); generally 500–2600 m |
| subsp. reflexa |
| | 8' Petals ± obovate to round; sepals < petals, generally ± acute; stem and pedicel hairs glandular or not; leaflet generally single-toothed; > 900 m |
| |
| | 10. Stem generally 5–20 cm; leaflet teeth < 10; sheathing leaf base generally appressed-hairy — generally glandular above; rocky areas, 2400–3800 m |
| subsp. pseudorupestris |
| | 10' Stem generally > 20 cm; leaflet teeth > 10; sheathing leaf base generally glabrous |
| |
| | 11. Petals ± yellow; inflorescence branches spreading (angle generally 20–40°), sometimes glandular above; Northwestern California, Cascade Range, n High Sierra Nevada, Modoc Plateau |
| subsp. ashlandica |
| | 11' Petals cream; inflorescence branches ascending (angle generally 10–30°), nonglandular above; Cascade Range, Sierra Nevada, Transverse Ranges, San Jacinto Mountains, East of Sierra Nevada |
| |
| | 12. Stem-base hairs < 1 mm, glandless; stem generally 20–60 cm; leaflet teeth generally single; 1800–3700 m |
| subsp. nevadensis |
| | 12' Stem-base hairs generally 2–3 mm, glandular; stem 40–90 cm; leaflet teeth generally double; 1200–2200 m |
| subsp. hansenii |
| | 5' Styles attached just below tip of fruit, slender throughout or widest near base |
| |
| | 13. Styles < or ± = 1 mm, tapered from rough-thickened base to tip |
| |
| | 14. Perennial; basal leaves generally present in flower; rocky alpine barrens, > 2700 m — leaflets densely hairy, at least below |
| |
| | 15. Leaf ± pinnate; leaflets 5–11, lobed ± 2/3 to midvein |
| P. pensylvanica |
| | 15' Leaf generally ± palmate; leaflets ± 5, lobed > 3/4 to midvein |
| P. pseudosericea |
| | 14' Annual (or short-lived perennial herb); basal leaves often withered or fallen in flower; generally moist or disturbed areas, < 3100 m |
| |
| | 16. Leaf pinnate, leaflets 9–17; petals > sepals, cream, ± obcordate — leaflets lobed > 1/2 to widvein; Modoc Plateau |
| 2 P. newberryi |
| | 16' Leaf generally ± palmate or ternate, leaflets 3–7; petals < sepals, yellow fading white, generally elliptic to obovate |
| |
| | 17. Stem-base hairs generally ± dense, glandular or not, < 1 mm, spreading or not; petals < 2.5 mm; hypanthium generally 2–4 mm wide; fruit smooth, < 1 mm, whitish or light brown; native |
| |
| | 18. Stem hairs glandular and not; leaflets 3, ± obovate; petals oblanceolate-elliptic |
| P. biennis |
| | 18' Stem hairs glandless; leaflets 3–5, oblanceolate to elliptic; petals obovate-elliptic |
| P. rivalis |
| | 17' Stem-base hairs sparse, glandless, < 2 mm, spreading; petals > 3 mm; hypanthium 3–10 mm wide; fruit veined, ± 1–1.5 mm, ± brown; alien |
| |
| | 19. Leaflets generally 3; petals 3–4 mm; anthers ± 0.3 mm; annual or short-lived perennial herb |
| P. norvegica |
| | 19' Leaflets generally 6–7; petals 6–9 mm; anthers ± 1 mm; short-lived perennial herb |
| 2 P. recta |
| | 13' Styles > 1 mm (except P. recta), generally slender — petals ± obcordate, > sepals |
| |
| | 20. Leaflets 3; inflorescence generally < 7-flowered — stem ± ascending to erect, generally < 30 cm (see also Fragaria, Sibbaldia) |
| |
| | 21. Leaflets lobed ± 1/2 to base, sparsely glandular; styles ± rough-thickened at base; Klamath Ranges |
| P. cristae |
| | 21' Leaflets not lobed, ± nonglandular; styles slender throughout; Klamath Ranges, High Cascade Range, High Sierra Nevada |
| |
| | 22. Teeth of central leaflet generally > 7, generally uneven, ± 1/4 to base; pedicel 10–20 mm; pistils > ± 20; stem ± glabrous or sparsely spreading-hairy; Klamath Ranges, High Cascade Range, High Sierra Nevada |
| P. flabellifolia |
| | 22' Teeth of central leaflet 7, even, 1/4–1/2 to base; pedicel 10–40 mm; pistils < ± 20; stem sparsely strigose; High Sierra Nevada |
| P. grayi |
| | 20' Leaflets > 3; inflorescence often > 7-flowered |
| |
| | 23. Leaf pinnate to subpalmate (see also Horkelia, Horkeliella, Ivesia) |
| |
| | 24. Annual to short-lived perennial herb; petals cream; styles 1–1.5 mm; fruit veined — leaflet lobes oblanceolate; receding shorelines; Modoc Plateau |
| 2 P. newberryi |
| | 24' Perennial; petals yellow; styles > 1.5 mm; fruit generally smooth |
| |
| | 25. Leaf densely white-tomentose below, green and strigose above; styles ± 1.5–2 mm — alpine barrens; n White and Inyo Mountains |
| P. morefieldii |
| | 25' Leaf surfaces similarly hairy (but hairs often denser below); styles 2–3 mm |
| |
| | 26. Basal leaf generally > 1/2 stem; pedicel generally ± recurved in fruit; < 2000 m |
| |
| | 27. Lateral leaflets toothed < 1/2 to base; pistils ± 5; stem 20–50 cm — South Coast, brackish meadows, presumed extinct |
| P. multijuga |
| | 27' Lateral leaflets toothed ± 1/2 or lobed ± fully to base; pistils generally > 10; stem 5–45 cm |
| |
| | 28. Leaflet ± 4-toothed ± 1/2 to base; pistils generally ± 10; plant ± subglabrous; c Central Coast, s Outer North Coast Ranges?, < 100 m |
| P. hickmanii |
| | 28' Leaflet 3–10-lobed > 1/2 to base; pistils 10–30; plant sometimes hairy; High Cascade Range, Great Basin Floristic Province, adjacent n High Sierra Nevada, 900–2000 m |
| P. millefolia |
| | 26' Basal leaf < 1/2 stem; pedicel ± straight in fruit; 1100–3700 m |
| P. drummondii |
| | 29. Petiole generally < blade, cottony-hairy; leaflets 3–7 per side, ± overlapped, palmately lobed > 1/2 to base — generally white-hairy |
| subsp. breweri |
| | 29' Petiole generally > blade, glabrous to shaggy-hairy; leaflets generally 2–4 per side, sometimes separated, pinnately toothed ± 1/2 to midvein, sometimes split to base |
| |
| | 30. Leaflets generally gray-hairy, ± overlapped; petiole generally densely straight- or shaggy-hairy |
| subsp. bruceae |
| | 30' Leaflets green, glabrous to ± hairy, generally separated; petiole glabrous or strigose |
| subsp. drummondii |
| |
| | 31. Stem ± prostrate or hanging, generally < 25 cm; inflorescence not flat-topped, pedicels often ± recurved in fruit; leaflet teeth < 10 — > 1800 m, s California Floristic Province, White and Inyo Mountains |
| |
| | 32. Leaflets densely white-tomentose below, green and strigose above; inflorescence generally 1–5-flowered — ± 3200 m; White and Inyo Mountains |
| P. concinna |
| | 32' Leaflet surfaces ± equally strigose; inflorescence generally > 5-flowered |
| |
| | 33. Plant hanging from rock crevices; fruits generally 5–20, ± smooth; pedicels generally > 15 mm; San Jacinto Mountains |
| P. rimicola |
| | 33' Plant rosetted to tufted in sandy soil; fruits generally > 15, ± veined; pedicels generally < 15 mm; s High Sierra Nevada, San Bernardino Mountains, San Jacinto Mountains |
| P. wheeleri |
| | 31' Stem ± ascending, generally 10–100 cm; inflorescence flat-topped, pedicels ± straight; leaflet teeth often > 10 |
| |
| | 34. Styles ± 1 mm, generally > 50; basal leaves generally fallen or withered in flower; stem short- and long-spreading-hairy; fruit veined; bractlets ± = sepals; alien |
| 2 P. recta |
| | 34' Styles generally 1.5–2 mm, < 50; basal leaves generally prominent in flower; stem glabrous or hairs of 1 length; fruit smooth; bractlets ± 1/2–2/3 sepals; native |
| |
| | 35. Leaflet base generally untoothed; stem 10–40 cm, base glabrous; anthers 0.4–0.9 mm; fruit 1.5 mm; 2600– 3500 m; c&s High Sierra Nevada |
| P. diversifolia var. diversifolia |
| | 35' Leaflet generally toothed or lobed ± throughout; stem 20–100 cm, base hairy; anthers 0.6–1.6 mm; fruit 1–1.5 mm; 120–3500 m; widespread |
| P. gracilis |
| | 36. Leaflet lobed > 3/4 to midvein; stem and petiole hairs generally appressed |
| |
| | 37. Longest petiole generally 5–10 cm; central leaflet 2–6 cm, lobes often narrowest at base, entire; petals 5–8 mm; widespread |
| var. elmeri |
| | 37' Longest petiole generally 10–25 cm; central leaflet 5–9 cm, lobes generally widest at base, often few-toothed; petals 7–10 mm; Modoc Plateau |
| var. flabelliformis |
| | 36' Leaflet toothed ± 1/2 or less to midvein; stem and petiole hairs spreading to appressed |
| |
| | 38. Leaf surfaces similarly hairy, not tomentose; petals generally 4–7 mm; longest petiole generally 5–15 cm; widespread, 800–3500 m |
| var. fastigiata |
| | 38' Leaf surfaces very different, generally tomentose below, dark and ± glabrous above; petals 7–10 mm; longest petiole 5–25 cm; nw Klamath Ranges, n Outer North Coast Ranges, 120–1100 m |
| var. gracilis
|