Potentilla breweri
Rosaceae tribe Potentilleae
Brewer's cinquefoil
prostrate to ascending, (0.5–)1–3(–4.5) dm, lengths 2–4(–5) times basal leaves.
alternate, rarely opposite, pinnately (palmately) compound (simple in Alchemilla, Aphanes, and Chamaerhodos);
stipules persistent (absent in Chamaerhodos), adnate to petiole;
venation pinnate or palmate.
pinnate with distal leaflets ± confluent, (2–)4–12(–17) × 1–2.5(–5) cm;
petiole 1–3(–7) cm, straight hairs mostly absent, cottony hairs sparse to dense, glands absent or obscured to common;
primary lateral leaflets 3–6 per side, on distal 1/2–2/3(–3/4) of leaf axis, ± overlapping, largest ones cuneate-flabellate, 0.5–1.5(–2.5) × 0.4–2(–3) cm, distal 1/2 to whole margin unevenly incised 1/2 to completely to midvein (blade often medially split as well), ultimate teeth or segments 3–10, narrowly elliptic, 2–10(–15) × 1–3(–5) mm, apical tufts less than 1 mm, surfaces grayish green to white, not glaucous, straight hairs sparse to common (sparser adaxially), loosely appressed to ascending, 1–1.5 mm, soft, cottony hairs sparse to dense, glands sparse or obscured to common.
1–3.
2–15(–25)-flowered, openly cymose.
(1–)1.5–2.5(–4) cm, straight in fruit.
epicalyx bractlets lanceolate to ovate, 2–5 × 1–1.5 mm;
hypanthium (3–)4–5 mm diam.;
sepals (3–)4–7 mm, apex acute;
petals 5–9(–10) × 4–8(–10) mm;
filaments (1–)2–4 mm, anthers (0.5–)1 mm;
carpels 15–25, styles 2–3 mm.
perianth and androecium perigynous;
epicalyx bractlets present, sometimes absent;
hypanthium usually patelliform, cupulate, or campanulate, sometimes turbinate, saucer-shaped, flat-bottomed, or subglobose to ellipsoid or ovoid;
torus flat to conic or turbinate, enlarged (absent or reduced in Alchemilla, Aphanes, and Chamaerhodos);
carpels 1–260, styles basal or lateral to subterminal, distinct;
ovules 1(or 2), basal.
aggregated achenes (achenes in Alchemilla and Aphanes);
torus sometimes fleshy;
styles deciduous or persistent, not elongate.
1.8 mm, smooth, not carunculate.
= 72–73, 99, 100, 102.
Potentilla breweri
Rosaceae tribe Potentilleae
Of conservation concern.
Potentilla breweri differs from other members of sect. Multijugae in its often dense, cottony vestiture. Density of cottony hairs and leaflet dissection can differ significantly between first-formed and mid- to late-season leaves of P. breweri; in the description above, leaves are those predominant at anthesis.
Potentilla breweri is most common in the Sierra Nevada of California, with sporadic occurrences to the Cascade Range in southern Washington. Disjunct populations occur in the Ruby and Snake ranges in Nevada and on Steens Mountain in Oregon, where often introgressed with P. versicolor. Reports from Utah are based on collections of P. concinna var. proxima or possible hybrids between P. concinna var. proxima and P. ovina var. decurrens.
J. Clausen et al. (1940) concluded that Potentilla breweri (with P. versicolor as synonym) belonged with P. bruceae and P. drummondii as members of a cenospecies that probably also included unnamed species (possibly P. ovina var. decurrens) from the mountains of Colorado, Utah, and Wyoming. Chromosome number varied within populations, and high numbers of univalents were present.
Recognition of Potentilla breweri as a distinct species differs from recent treatments in which it was considered to be a variety or subspecies of P. drummondii, parallel to the treatment of P. bruceae. The present continental perspective of the genus, as well as additional fieldwork, has resulted in the return of all three to species rank (B. Ertter and D. Mansfield 2007). Placement of P. breweri in sect. Multijugae, separate from P. bruceae and P. drummondii in sect. Graciles, is based on the commonly prostrate habit, fully pinnate leaves, and deeply divided overlapping leaflets.
Although B. C. Johnston (1980) used Potentilla breweri var. viridis Jepson to accommodate greener-than-average sparsely cottony plants, including populations treated here as P. versicolor, the type is probably a sterile hybrid with P. wheeleri as one parent (B. Ertter 1992). The type of P. millefolia var. algida Jepson (included by Johnston in the synonymy of var. viridis) and comparable plants from north-central California combine features of P. breweri and P. versicolor but are more glandular than either. This variant, as well as exceptionally small plants from the Warner Mountains of California, may prove distinct.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 14–22, species ca. 860 (14 genera, 189 species, including 1 hybrid, in the flora area).
The base chromosome number for Potentilleae is mostly x = 7 (8 in Alchemilla and Aphanes; 14 in Comarum).
Variation in the number of genera recognized in Potentilleae is due to differences in generic delimitation between D. Potter et al. (2007) and the authors of Potentilla and segregates here (see 9. Ivesia and 8. Potentilla for discussion). In the former, Duchesnea, Horkelia, Horkeliella, and Ivesia are included within Potentilla. Likewise, Aphanes is included within Alchemilla by Potter et al. while it is kept distinct here.
Potentilla and its segregates and Fragaria are host to Phragmidium rusts, but not the other genera of the tribe.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Shrubs; leaf lobe margins entire; achenes hirsute. | Dasiphora |
1. Herbs, perennial, sometimes annual or biennial, or subshrubs; leaf lobe margins or apices ± toothed, sometimes entire; achenes glabrous (sometimes ± hairy) | → 2 |
2. Petals 0, sepals 4; achenes 1, enclosed in dry, urceolate or subglobose to ellipsoid or ovoid hypanthia | → 3 |
2. Petals and sepals usually 5; achenes 1–260, usually aggregated (sometimes on elongating tori), usually in (± open) patelliform, cupulate, campanulate, or turbinate hypanthia (not enclosed in dry hypanthium) | → 4 |
3. Herbs perennial; leaves basal, blades reniform to orbiculate, palmately lobed, sometimes palmately compound; stamens 4. | Alchemilla |
3. Herbs annual; leaves cauline, blades cuneate, deeply divided into segments, each lobed; stamen 1(or 2). | Aphanes |
4. Leaves all or mostly basal or proximal (if cauline, deeply pinnatifid), ternate or 2–4-ternate (sometimes simple and coarsely toothed apically in Sibbaldia) | → 5 |
4. Leaves basal or cauline, the latter usually reduced distally, odd-pinnate to palmate, rarely ternate or ± bipinnate | → 9 |
5. Tori becoming red and fleshy in fruit; leaf margins serrate to crenate | → 6 |
5. Tori hemispheric (not enlarged or fleshy) in fruit or absent; leaf margins entire or (2–)3(–5)-toothed apically | → 7 |
6. Leaves ± doubly serrate or crenate; stolons leafy; inflorescences: flowers solitary, axillary at stolon nodes; petals yellow. | Duchesnea |
6. Leaves serrate to crenate; stolons not leafy; inflorescences 1–10-flowered, cymes, axillary from leaf rosettes; petals usually white. | Fragaria |
7. Leaves pinnately compound or simple and deeply pinnatifid, margins entire, stipules absent. | Chamaerhodos |
7. Leaves ternate, margins toothed apically, stipules persistent | → 8 |
8. Petals ± yellow; stamens 5. | Sibbaldia |
8. Petals usually white; stamens 20(–30). | Sibbaldiopsis |
9. Petals deep red to purple, rarely pink, shorter than sepals; tori enlarged and spongy at maturity; horizontal stems sometimes floating, wetland habitats. | Comarum |
9. Petals yellow to white, rarely pink or red (then equal to or longer than sepals); tori not enlarged and spongy at maturity; stems erect to decumbent, not horizontal or floating even if in wetlands | → 10 |
10. Anthers dehiscing by continuous marginal slit (with a single theca); styles sub-basal. | Drymocallis |
10. Anthers dehiscing longitudinally; styles subterminal to lateral | → 11 |
11. Hypanthium patelliform to campanulate or cupulate to turbinate (not flat-bottomed); filaments not forming tube; petals white to yellow, sometimes reddish or pink tinged | → 12 |
11. Hypanthium ± cupulate or bluntly campanulate and flat-bottomed; filaments forming tube; petals usually white, sometimes pink-tinged, rose-veined, or cream | → 13 |
12. Plants not aromatic; leaves ± cordate or reniform to narrowly elliptic in outline, leaflets 3–15(–41); petals oblanceolate or obovate to obcordate to nearly round, rarely elliptic; carpels 3–260. | Potentilla |
12. Plants often aromatic; leaves planar to cylindric, leaflets (3–)7–161; petals linear or narrowly oblanceolate to obovate, sometimes obcordate; carpels 1–20(–40). | Ivesia |
13. Stamens 10; leaflets (3–)5–41. | Horkelia |
13. Stamens 20; leaflets 30–70. | Horkeliella |
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