Potentilla rivalis
Potentilla erecta
brook cinquefoil, brook or river cinquefoil, river cinquefoil, streambank cinquefoil
erect cinquefoil, tormentil
decumbent to erect, sometimes prostrate, (0.5–)1–4(–7) dm, hairs at base not stiff, not tubercle-based, glands absent or sparse, inconspicuous.
mostly ascending to erect, not flagelliform, openly branched, not rooting at nodes, (0.5–)1–5(–7) dm.
ternate, palmate, or subpalmate (with distal leaflets ± confluent), basal 3–15(–25) cm, cauline 2–7(–12) cm;
petiole: basal 1–9(–16) cm, cauline 0.5–4(–8) cm, long hairs usually common to abundant, ascending to spreading, 0.5–1.5 mm, usually ± weak, ± crisped hairs common to abundant, glands absent or sparse, inconspicuous;
leaflets 3–5(–7), at tip to distal 1/5 (basal) or 1/2 (cauline) of leaf axis, separate to ± overlapping, largest ones oblanceolate-elliptic to obovate, (0.5–)1–5(–6) × 0.5–2(–2.5) cm, distal 1/2–3/4 of margin evenly to unevenly incised 1/3–1/2 to midvein, sometimes cleft nearly to base, teeth 3–8 per side, surfaces moderately to abundantly hairy, glands absent or sparse.
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.
(5–)20–100+-flowered.
3–30-flowered, cymose, open.
0.2–1(–2) cm.
(1–)2–3(–5) cm.
epicalyx bractlets narrowly elliptic to ovate, (1.5–)2–4(–6) × 0.8–1.5 mm;
hypanthium (2–)3–5 mm diam.;
sepals 3–5 mm, apex broadly acute to obtuse;
petals pale yellow to yellow, broadly oblong-obovate, 1.5–2 × 1 mm;
stamens (5–)10(–15), filaments 0.4–0.9 mm, anthers 0.2–0.3 mm;
carpels 40–100, styles 0.5–0.6 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.
yellowish, 0.7–0.9 mm, ± smooth, without a corky protuberance.
1.2–2 mm, rugose.
erect to horizontal, irregularly thickened, 1–8 cm.
= 14, 70.
= 28 (Eurasia).
Potentilla rivalis
Potentilla erecta
Potentilla rivalis is most abundant in central and western North America; reports of occurrences in more eastern states (including those listed here) need confirming, as P. rivalis and P. norvegica often have been confused. Potentilla leucocarpa Rydberg was provided as a superfluous replacement name for P. millegrana; specimens annotated by Rydberg with this name include both P. biennis and P. rivalis.
Potentilla rivalis is sometimes divided into three species or varieties (for example, H. J. Scoggan 1978–1979). In a strict sense, var. rivalis has subpalmately compound (5-foliate) leaves. Variety milligrana, the most common phase, has 3-foliate leaves. Plants with both 3- and 5-foliolate leaves are var. pentandra, which also tends to have five stamens, though this latter character is not correlated with the leaf features. On the Great Plains, where var. pentandra is confined, all three expressions are often found in a single population (R. L. McGregor 1986b).
(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.)
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