Potentilla sect. Potentilla
Potentilla erecta
erect cinquefoil, tormentil
usually becoming ± prostrate, sometimes ascending to erect, often flagelliform, often rooting at nodes, lateral or central to persistent or ephemeral basal rosettes, 0.3–12+ dm, lengths (1–)2–10+ times basal leaves.
mostly ascending to erect, not flagelliform, openly branched, not rooting at nodes, (0.5–)1–5(–7) dm.
basal and cauline not in ranks;
cauline (proximal to flowering and/or branching nodes) 0–3(–7);
primary leaves ternate or palmate, 2–20(–30) cm;
petiole: long hairs appressed to spreading, weak to stiff, glands absent or sparse, sometimes common;
leaflets 3–5(–7), at tip of leaf axis, separate to slightly overlapping, obovate to narrowly elliptic, cuneate, or oblanceolate, margins flat or slightly revolute, distal 1/2–3/4 evenly incised 1/4–1/2 to midvein, teeth 2–13 per side, surfaces similar to ± dissimilar, abaxial usually green, sometimes silvery white, cottony hairs absent, adaxial green, not glaucous, long hairs usually ± stiff, sometimes weak or absent.
ephemeral, usually ternate, 2–15 cm;
petiole (1–)3–13 cm, long hairs sparse to common, appressed, 0.5–1 mm, stiff, glands absent;
leaflets 3(–5), central ± obovate to cuneate, (0.5–)1–2 × (0.3–)1–1.5 cm, distal 1/2–2/3 of margin incised ± 1/3 to midvein, teeth 2–4 per side, surfaces similar, green (abaxial sometimes paler), glabrate or sparsely to moderately hairy.
(0–)1–3(–7) proximal to 1st flowering node, expanded at anthesis, usually ternate, rarely palmate (or appearing so because of leafletlike stipules), (0.5–)1–3 cm;
petiole usually 0 cm;
leaflets 3(–5), usually much narrower than those of basal leaves, narrowly cuneate to oblanceolate, (0.5–)1–3 × (0.2–)0.5–1 cm, distal 1/3–2/3 of margin incised ± 1/2 to midvein, teeth 2–4(–6) per side, apex usually obtuse to acute.
solitary flowers at stolon nodes or 3–30-flowered, cymose, open.
3–30-flowered, cymose, open.
straight or slightly curved in fruit, (1–)2–12(–17) cm, proximal not longer than distal.
(1–)2–3(–5) cm.
4–5(–10)-merous;
hypanthium 1.5–5(–7) mm diam.;
petals usually bright yellow, rarely cream, ± obcordate or obovate to round, (2–)4–9(–12) mm, usually longer than sepals, apex rounded to retuse;
stamens 15–20;
styles subapical, columnar-clavate to ± filiform, not papillate-swollen proximally, 0.6–1.5 mm.
4(–5)-merous;
epicalyx bractlets ovate to narrowly elliptic, 1.5–4 × 0.5–1 mm, much smaller than to sometimes equal to sepals;
hypanthium 1.5–2.5 mm diam.;
sepals (2–)3–5 mm, apex broadly acute;
petals (2–)4–6 × (1.5–)3–6 mm, apex ± retuse;
stamens 15–20, filaments 2–3.8 mm, anthers 0.4–0.6 mm;
carpels 4–8(–20), styles 0.9–1.4 mm.
smooth or rugose.
1.2–2 mm, rugose.
erect to horizontal, irregularly thickened, 1–8 cm.
= 28 (Eurasia).
Potentilla sect. Potentilla
Potentilla erecta
Species 7 or 8 (5 in the flora).
The species of sect. Potentilla comprise a monophyletic clade that includes Duchesnea, diverging basally to the species placed here in Horkelia, Horkeliella, and Ivesia (C. Dobeš and J. Paule 2010; M. H. Töpel et al. 2011). There are at least some morphological features by which this and other clades basal to the core Potentilla could be treated as separate genera. However, since the type of the genus (P. reptans) is in this section, doing so would require either a massive renaming of most Potentilla, or else conserving the type of the genus on a different species. If the latter course were taken, the species in this section would comprise Tormentilla.
Among the distinctive features of sect. Potentilla are the high percentage of stoloniferous species (shared with Duchesnea), a tuberous rootstock in many species, and the presence of tetramerous-flowered species (P. anglica, P. erecta). The section is also distinctive in having an amphi-Atlantic distribution, with native species in both eastern North America and Europe. The native material has sometimes been treated as a single species, or with confused nomenclature (M. L. Fernald 1931), leading to much unreliability in older herbarium annotations.
When leaves are palmate, the lateral leaflet pairs are usually more or less fused at the base, suggesting a ternate origin. Distal cauline leaves and inflorescence bracts are sometimes opposite. For comparison with other sections, counts of cauline leaves are restricted to nodes proximal to the first flowering stolon node, but descriptions of cauline leaves otherwise include all well-developed foliar structures at stolon nodes (until such time as these root and form new basal rosettes).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Although included here, Potentilla erecta is questionably extant as a naturalized species in North America and is not currently known from Newfoundland where historically reported. It is a medicinal plant called tormentil, high in tannins and strongly astringent. A tea made from the tuberous rootstock is widely used in Europe and parts of Asia for diarrhea, dysentery, sore throats, and related problems. A decoction is a mild antibiotic used for cuts and minor infections, especially as an anti-inflammatory for gingivitis and other gum problems. The rootstock is used as a red dye.
Another synonym with a long history of use is Potentilla tormentilla Necker, illegitimate by virtue of being superfluous.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Flowers 4(–5)-merous; stems usually openly branched; leaflets 3–5; hypanthia 1.5–4 mm diam | → 2 |
1. Flowers 5(–10)-merous; stems not branched; leaflets (3–)5(–7); hypanthia 2.5–7 mm diam | → 3 |
2. Stems soon becoming prostrate, ± flagelliform, eventually rooting at some nodes; inflorescences mostly solitary flowers at stolon nodes; cauline leaves: petioles 0.3–4(–8) cm; basal leaves ± persistent. | P. anglica |
2. Stems mostly ascending to erect, not flagelliform, not rooting at nodes; inflorescences cymose, 3–30-flowered; cauline leaves: petioles usually 0 cm; basal leaves ephemeral. | P. erecta |
3. Petals 7–9(–12) × 6–9(–11) mm; anthers (1–)1.3–2 mm; epicalyx bractlets elliptic or oblong to ovate, 4–10 × 1.5–3.5 mm, often much larger than sepals (especially in fruit); petiole hairs tightly to loosely appressed, 0.5–1.5 mm, leaflet surfaces similar, abaxial green, sparsely to moderately hairy; cauline leaves 2–3(–4) proximal to 1st flowering node; achenes ± rugose; introduced. | P. reptans |
3. Petals 4–7(–8) × 3–6.5(–8) mm; anthers 0.4–1 mm; epicalyx bractlets linear to narrowly lanceolate or lanceolate-elliptic, 2–5(–6) × 0.8–1.5(–2) mm, slightly smaller than to larger than sepals (especially in bud); petiole hairs appressed to spreading, (0.5–)1–3 mm, leaflet surfaces similar to ± dissimilar, abaxial green to silvery white, sparsely to densely hairy; cauline leaves 0–1 proximal to 1st flowering node; achenes smooth or faintly rugose; native | → 4 |
4. Cauline leaves not fully expanded at anthesis, 0–1 proximal to 1st flowering node, leaflets ± resembling those of basal leaves, apex rounded to obtuse, teeth 2–7 per side on distal 1/2 of leaflet; rootstocks erect, stout, 0.5–2 cm. | P. canadensis |
4. Cauline leaves well expanded at anthesis, (0–)1 proximal to 1st flowering node, leaflets often more elongate than those of basal leaves, apex acute to obtuse, teeth 4–8(–13) per side on distal 1/2–3/4 of leaflet; rootstocks horizontal, irregularly thickened or moniliform, 1–8 cm. | P. simplex |
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