Potentilla sect. Subjugae
Rosaceae tribe Potentilleae
ascending to nearly erect, not flagelliform, not rooting at nodes, lateral to persistent basal rosettes, (0.2–)0.4–2.5(–3.5) dm, lengths 2–3 times basal leaves.
basal not 2-ranked;
cauline 0–3;
primary leaves palmate with additional lateral pairs to pinnate (with distal leaflets distinct), (1–)1.5–10(–14) cm;
petiole: long hairs spreading to tightly appressed, weak to stiff, glands absent or sparse;
leaflets 5–7(–9), on distal 1/10–1/3(–1/2) of leaf axis, strongly overlapping or not, oblanceolate-oblong to obovate, margins scarcely to ± revolute, ± whole length evenly incised 1/2–3/4 to midvein, teeth 2–9 per side, surfaces ± to strongly dissimilar, abaxial white to grayish green, cottony hairs sparse to dense, adaxial green to grayish, not glaucous, long hairs ± stiff.
alternate, rarely opposite, pinnately (palmately) compound (simple in Alchemilla, Aphanes, and Chamaerhodos);
stipules persistent (absent in Chamaerhodos), adnate to petiole;
venation pinnate or palmate.
(1–)2–20(–30)-flowered, usually cymose, open.
straight in fruit, 0.5–2(–3) cm, proximal ± longer than distal.
5-merous;
hypanthium 3–5 mm diam.;
petals yellow, ± obcordate, 4–8 mm, equal to or longer than sepals, apex retuse;
stamens ca. 20;
styles subapical, filiform to filiform-tapered or filiform-columnar, papillate-swollen in proximal less than 1/5 if at all, 0.8–2 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.
smooth.
Potentilla sect. Subjugae
Rosaceae tribe Potentilleae
Species 2 (2 in the flora).
Section Subjugae is used primarily to accommodate the unique leaf dissection and vestiture of Potentilla subjuga, which commonly has five palmately arranged leaflets and one, sometimes two, additional pairs of lateral leaflets. Sometimes leaves are simply pinnate with only three terminal leaflets, and sufficient intergradation occurs with P. saximontana that it is also included in the section. This circumscription coincides with the initial concept of Rydberg and Nelson and contrasts with that of B. C. Johnston (1980, 1985).
Section Subjugae is restricted to subalpine and alpine habitats in the Rocky Mountains and adjacent ranges of western North America centered in Colorado. Variation within the section is complex and poorly understood, such that the two species treated here represent only the best expressed extremes with existing names. Other named components of uncertain placement include Potentilla lupina Rydberg, P. minutifolia Rydberg, P. rubricaulis var. nana Clements & E. G. Clements, P. rubripes Rydberg [= P. concinna var. rubripes (Rydberg) C. L. Hitchcock], and P. tenerrima Rydberg.
(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. Leaflets at tip of leaf axis (3–)5; styles 1.5–2 mm; stems (0.8–)1–2.5(–3.5) dm; inflorescences 3–20(–30)-flowered. | P. subjuga |
1. Leaflets at tip of leaf axis 3; styles 0.8–1.5 mm; stems (0.2–)0.4–1(–1.5) dm; inflorescences (1–)2–5(–10)-flowered. | P. saximontana |
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 |
