Potentilla sect. Subviscosae
Rosaceae tribe Potentilleae
± prostrate to decumbent, sometimes pendent (on rock faces), not flagelliform, not rooting at nodes, lateral to persistent basal rosettes, 0.2–2(–3) dm, lengths 1–3(–5) times basal leaves.
basal not in ranks;
cauline 0–2;
primary leaves ternate or palmate, (1–)2–10(–18) cm;
petiole: long hairs usually spreading to ascending, sometimes loosely appressed, weak to stiff, glands usually abundant, sometimes sparse;
leaflets 3–5(–7), at tip of leaf axis, separate to slightly overlapping, oblanceolate or elliptic to broadly obovate or cuneate to flabellate, sometimes nearly orbiculate, margins flat, distal 1/3–3/4 evenly to unevenly (P. subviscosa) incised 1/5–3/4 to midvein, sometimes deeply lobed as well (P. subviscosa), teeth (1–)2–4(–9) per side, surfaces similar, green to gray-green, not glaucous, long hairs weak to stiff, cottony hairs absent.
alternate, rarely opposite, pinnately (palmately) compound (simple in Alchemilla, Aphanes, and Chamaerhodos);
stipules persistent (absent in Chamaerhodos), adnate to petiole;
venation pinnate or palmate.
solitary flowers or 2–10(–20)-flowered, usually ± cymose, open, sometimes racemiform when prostrate.
usually recurved in fruit, 0.5–2(–4) cm, proximal usually not much longer than distal.
5-merous;
hypanthium 2–6 mm diam.;
petals pale to bright yellow, narrowly or ± obcordate, rarely broadly obovate, (2–)3–7(–8) mm, longer than sepals, apex usually ± retuse;
stamens 15–20;
styles subapical, usually filiform, sometimes tapered-columnar (P. cottamii), papillate-swollen in proximal 1/10(–1/3 in P. cottamii), (1–)1.5–2.5(–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.
smooth to ± rugose.
Potentilla sect. Subviscosae
Rosaceae tribe Potentilleae
Species ca. 10 (7 in the flora).
Section Subviscosae consists of species that have radiated in the sky islands of southwestern North America and Mexico, mostly in rocky meadows or outcrops in forested montane areas (B. Ertter 2007c). Some species are chasmophytic, forming clumps on cliffs or steep rock outcrops, similar to species in Ivesia sect. Setosae. Mexican species are poorly known but include at least Potentilla mexiae Standley and possibly P. rydbergiana Rose, as well as undescribed taxa.
Section Subviscosae shares with sect. Concinnae leaves that are often palmate, prostrate stems, and slender pedicels that become recurved in fruit, as well as a similar biogeographic pattern. Section Subviscosae differs in that cottony and strongly verrucose hairs are lacking, leaves are never strongly bicolored, and petiole and stem hairs are spreading to loosely appressed. Vestiture consists of varying proportions of long hairs, short hairs, and glands; petals are often somewhat clawed, unlike the unclawed norm in the genus.
(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. Basal leaves usually ternate, rarely palmate | → 2 |
1. Basal leaves usually palmate, rarely ternate | → 4 |
2. Petals (2–)3–4 mm; styles 1–1.5 mm; ne Nevada, nw Utah. | P. cottamii |
2. Petals 3–8 mm; styles 2–3 mm; se Arizona | → 3 |
3. Petioles: long hairs 1–2(–3) mm; central leaflets with 2–3(–4) teeth per side; Santa Rita, Huachuca, and Chiricahua ranges. | P. rhyolitica |
3. Petioles: long hairs 0.5–1(–1.5) mm; central leaflets with 3–5(–6) teeth per side; Pinaleño Mountains, nearby Mogollon Rim, and Santa Catalina Range. | P. albiflora |
4. Petals nearly white abaxially, pale yellow adaxially, narrowly obcordate; central leaflets evenly to unevenly incised (sometimes deeply lobed as well), teeth 2–9 per side; short hairs well differentiated from long hairs, ± abundant to dense throughout. | P. subviscosa |
4. Petals ± paler abaxially, bright yellow adaxially, ± obcordate; central leaflets evenly incised, teeth 2–4(–5) per side; short hairs not well differentiated from long hairs, absent or sparse throughout | → 5 |
5. Plants rooted in ground; leaflets gray-green, long hairs abundant to dense; carpels ca. 20, styles (1.2–)1.5–2 mm; s Sierra Nevada and San Bernardino Mountains, California. | P. wheeleri |
5. Plants rooted in rock crevices, often on vertical surfaces; leaflets green, long hairs sparse to abundant; carpels 5–15(–20), styles 1.5–2.5 mm; s California, nw Arizona, and Baja California, Mexico | → 6 |
6. Central leaflets 1–3 cm, oblanceolate to broadly obovate-cuneate or nearly orbiculate, distal ± 1/3 of margins incised ± 1/4 to midvein; epicalyx bractlets lanceolate-elliptic, rarely linear; San Jacinto Mountains, California, and Baja California, Mexico. | P. rimicola |
6. Central leaflets 0.5–1.5(–2) cm, oblanceolate, distal ± 3/4 of margins incised 1/2–3/4 to midvein; epicalyx bractlets ovate-elliptic; Hualapai Mountains, Arizona. | P. demotica |
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 |
