Potentilla canadensis |
Potentilla tikhomirovii |
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dwarf cinquefoil |
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Habit | Plants ± tufted. | |
Caudex branches | slender to stout, not columnar, not sheathed with marcescent whole leaves. |
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Stems | initially ascending to erect, soon becoming prostrate, flagelliform, not branched, eventually rooting at some nodes, (0.3–)0.5–12 dm. |
± ascending, sometimes nearly erect, 0.5–1.5(–3) dm, lengths 2–4 times basal leaves. |
Basal leaves | ± persistent, usually palmate, 2–9(–11) cm; petiole 1–7(–8) cm, long hairs abundant to dense, appressed to spreading, 1.5–3 mm, mostly ± weak, glands absent or sparse; leaflets (3–)5(–7), central mostly ± obovate to cuneate, sometimes narrowly so, (0.5–)1–4(–6) × (0.5–)0.8–2(–3) cm, distal 1/2 of margin incised 1/4–1/3 to midvein, teeth 2–7 per side, surfaces similar to ± dissimilar, abaxial green to silvery white, sparsely to densely hairy, adaxial green, sparsely to moderately hairy. |
2–4 cm; petiole 1–2.5 cm, long hairs common to abundant, spreading to ascending, rarely loosely appressed, 1–2 mm, ± stiff, verrucose, short-crisped hairs sparse to abundant, sometimes nearly absent, cottony hairs absent, glands sparse; leaflets ± overlapping, central elliptic to obovate, 1–1.5 × 0.6–1.1 cm, petiolulate, base broadly cuneate, margins flat or slightly revolute, distal ± 2/3 incised ± 1/2 to midvein, teeth (3–)4 per side, ± approximate, surfaces ± dissimilar, abaxial reddish or greenish gray to white, long hairs 1 mm, cottony-crisped hairs common to dense, adaxial green or reddish to gray-green, long hairs sparse to abundant, short-crisped hairs absent or sparse to common. |
Cauline leaves | 0–1 proximal to 1st flowering node, not fully expanded at anthesis, usually palmate, 2–7(–9) cm; petiole (0.5–)1–6(–7.5) cm; leaflets (3–)5, ± resembling those of basal leaves, apex rounded to obtuse. |
0–1. |
Inflorescences | solitary flowers at stolon nodes. |
2–5-flowered. |
Pedicels | (1–)2–5(–9) cm. |
1–2 cm in flower, to 3(–5) cm in fruit. |
Flowers | 5-merous; epicalyx bractlets linear to lanceolate-elliptic, (2–)3–5(–6) × 0.8–1.5 mm, slightly smaller than to ± equal to sepals; hypanthium 2.5–5 mm diam.; sepals (2–)3–5(–6) mm, apex acute; petals 4–6(–8) × 3.5–6.5(–8) mm, apex rounded to slightly retuse; stamens ca. 20, filaments 0.5–2 mm, anthers 0.4–1 mm; carpels 20–40, styles 0.8–1.4 mm. |
epicalyx bractlets narrowly elliptic to narrowly ovate, 4–6 × 1–2.5 mm, (1/2–)2/3 to as wide as sepals, margins revolute, sometimes flat, red glands usually common, conspicuous; hypanthium 3.5–4.5 mm diam.; sepals 5–7 mm, apex subacute; petals 6–8 × (4–)5–8 mm, longer than sepals; filaments 0.7–1.2 mm, anthers 0.4 mm; carpels 40–60, apical hairs absent, styles columnar, strongly papillate-swollen in proximal 1/5–1/3, 0.9–1 mm. |
Achenes | 1.2–1.4 mm, smooth. |
1.2–1.8 mm. |
Rootstocks | erect, stout, 0.5–2 cm. |
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2n | = 28. |
= 42, 49 (Russian Far East). |
Potentilla canadensis |
Potentilla tikhomirovii |
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Phenology | Flowering late Mar–early Jun. | Flowering summer. |
Habitat | Dry flats and slopes in lawns, pastures, roadsides, cherty slopes, dry meadows, edges of oak and conifer woodlands, often on acidic soil | Dry tundra meadows, loamy soil banks, sedge-herb slopes |
Elevation | 0–1500 m (0–4900 ft) | 0–1100 m (0–3600 ft) |
Distribution |
CT; DC; DE; KY; MA; MD; ME; MO; NC; NH; NJ; NY; OH; PA; RI; SC; TN; VA; VT; WV; NS; ON
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AK; NT; NU; Greenland; Europe (Russia); Asia |
Discussion | A cream-colored form (ochroleuca) was described from a now-obliterated site in Massachusetts (M. L. Fernald 1931). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Potentilla tikhomirovii is an assumed hybrid species combining characteristics from P. arenosa subsp. arenosa of sect. Niveae (abaxial leaflet surfaces with crisped-cottony hairs, adaxial surfaces with both long and short hairs, petioles often with both long and short hairs, and flower shape and size) and P. hyparctica of sect. Aureae (crisped-cottony hairs often not fully covering abaxial leaf surfaces, reddish color in most plant parts, sepals and epicalyx bractlets relatively large, broad, less acute, and with many and reddish glands, which are often also on petioles and stipules). Potentilla tikhomirovii has an interrupted range and is not very coherent morphologically. It forms large populations locally, probably by agamic seed propagation, and is a significant part of the Potentilla variation in northern and northeastern Greenland, Ellesmere Island, and parts of the Brooks Range, northern Alaska. Both the distributional and the morphologic patterns indicate that it has evolved multiple times in different regions, such that it is a borderline case for status as an independent species. Its large populations and significant distribution in some regions support recognition, as also does the paucity of obvious back-crosses with the parents. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 9, p. 134. | FNA vol. 9, p. 201. |
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Potentilla | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Niveae |
Sibling taxa | ||
Synonyms | P. canadensis var. pumila, P. canadensis var. villosissima, P. caroliniana, P. pumila | |
Name authority | Linnaeus: Sp. Pl. 1: 498. (1753) | Jurtzev: in A. I. Tolmatchew, Fl. Arct. URSS 9(1): 318. (1984) |
Web links |