Potentilla bipinnatifida |
Potentilla effusa |
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bipinnate cinquefoil, potentille bipinnatifide, tansy cinquefoil |
branch cinquefoil |
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Stems | ascending to erect, (1–)2–5 dm. |
(0.5–)1.5–4(–5.5) dm, lengths 2–3(–4) times basal leaves. |
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Basal leaves | subpinnate to subpalmate, (6–)10–25 cm; petiole (2–)5–15 cm, long hairs dense, appressed, 1–2 mm, soft to ± stiff, short hairs absent, crisped hairs sparse, glands absent, sparse, or obscured; leaflets 2–3 per side, on distal 1/6–1/3(–1/2) of leaf axis, separate to ± overlapping, terminal ones oblanceolate, (2–)3–6(–10) × 1–2(–3.5) cm, margins revolute, incised 3/4+ to midvein, undivided medial blade 1.5–6 mm wide, teeth 5–8 per side, ± linear, surfaces ± to strongly dissimilar, abaxial usually white, rarely grayish, long hairs abundant especially on veins, 1–2 mm, ± weak, short hairs absent or obscured, cottony (and crisped) hairs ± dense, glands absent or obscured, adaxial green to grayish, long hairs sparse to abundant, loosely appressed, 0.5–1.5 mm, short hairs absent or sparse, crisped and/or cottony hairs sparse to common, glands sparse to common. |
pinnate, (3–)5–15(–25) cm; petiole 0.5–5(–8) cm, long hairs absent to abundant, ± appressed, 1–3 mm, stiff to weak, short and crisped hairs absent or obscured, cottony hairs abundant (at least on first-formed leaves), glands sparse or obscured; leaflets not conduplicate, lateral ones evenly to unevenly paired, 2–5(–7) per side (secondary leaflets sometimes interspersed) on distal 1/3–1/2 of leaf axis, distal pairs usually not decurrent or confluent with terminal leaflet, larger leaflets oblanceolate to narrowly obovate, 1–2.5(–3) × 0.3–1.3(–1.8) cm, distal (1/2–)2/3–3/4 (rarely more) of margin incised ± 1/2 to midvein, teeth (1–)2–9 per side, 1–4 mm, surfaces similar, gray to white or ± green, abaxial: long hairs sparse to common (at least on veins), 0.5–1.5 mm, weak to stiff, short or crisped hairs absent or sparse, sometimes obscured, cottony hairs absent or sparse to dense, glands absent, sparse, or obscured, adaxial: long hairs absent or sparse to common, short or crisped hairs absent or sparse, cottony hairs absent or sparse to abundant, glands absent or sparse. |
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Cauline leaves | 2–4. |
2–6+. |
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Inflorescences | (4–)10–50(–100)-flowered, congested or elongating in fruit. |
7–30-flowered. |
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Pedicels | 0.2–0.8 cm (proximal to 2 cm). |
0.3–3 cm. |
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Flowers | epicalyx bractlets narrowly elliptic to lanceolate, 2.5–6 mm, lengths ± 2/3 times sepals, margins flat; hypanthium 3–5 mm diam.; sepals 3–6 mm, apex ± acute, abaxial surfaces: venation indistinct, glands absent, sparse, or obscured; petals yellow, 3–5 × 3–4 mm, lengths ± equal to sepals; filaments 0.5–2 mm, anthers 0.3–0.5 mm; carpels 50–80, styles papillate-swollen in proximal 1/2–3/4+, 1–1.2 mm. |
epicalyx bractlets linear to narrowly lanceolate, 1–2.5(–3) × 0.3–1 mm, 1/2–2/3 as long as sepals, abaxial vestiture often much sparser than sepals, often glabrate or glabrescent distally, straight hairs absent or sparse, cottony hairs usually abundant (at least proximally), sometimes absent or nearly so (var. rupincola); hypanthium 2–6 mm diam.; sepals 3–6(–7) mm, apex long acuminate; petals 4–6.5 × 4–6 mm; filaments 1–3.5 mm, anthers 0.5–1 mm; carpels 3–15, styles 1.5–2.1 mm. |
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Achenes | 1–1.2 mm, smooth to faintly rugose. |
1.8–2.1 mm, smooth. |
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2n | = 56. |
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Potentilla bipinnatifida |
Potentilla effusa |
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Phenology | Flowering summer. | |||||
Habitat | Open shortgrass prairie, alkaline bottoms, streamsides in sagebrush, disturbed sites | |||||
Elevation | 10–3400 m (0–11200 ft) | |||||
Distribution |
AK; CO; ID; MI; MN; MT; ND; NE; NM; SD; UT; WY; AB; MB; NT; ON; QC; SK; YT
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CO; ID; MN; MT; ND; NE; NM; SD; UT; WY; AB; MB; SK |
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Discussion | Potentilla bipinnatifida is similar to P. litoralis in habit and leaf dissection but has flat, silky epicalyx bractlets and sepals with no evident glands. Vestiture is generally silkier, and the silvery to bicolor leaves are white-cottony abaxially. The two species are sympatric in the plains of Canada, with some intergradation; P. bipinnatifida is also common south to Colorado, where it is found in intermontane meadows and sagebrush flats. Outlying populations occur in Blaine and Custer counties, Idaho, and Duchesne and Piute counties, Utah. Eastern collections from disturbed sites might be adventive. Potentilla missourica Hornemann ex Lindley and P. normalis Besser ex Sprengel are older names for this species; both were rejected against a conserved P. bipinnatifida with designated lectotypes (see J. Soják 2008b). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (2 in the flora). In the southern Rocky Mountains, Potentilla effusa is relatively distinct from P. hippiana both morphologically and geographically, with P. effusa mostly east of the Continental Divide and P. hippiana mostly west. In general, P. hippiana differs from P. effusa in having leaflets more evenly paired, more tightly serrate with teeth often occurring on the whole margin, and more bicolored with abaxial vestiture of crisped rather than cottony hairs. Stems of P. effusa have more cauline leaves on average than P. hippiana, and vestiture of epicalyx bractlets of P. effusa (as here circumscribed) is never sericeous. The distinction between the two species is marred by intermediate populations throughout their shared range in the northern Rocky Mountains and Great Plains. Most regional floras focused on these areas have accordingly included Potentilla effusa within P. hippiana, sometimes without infraspecific distinction. An alternate solution has been the recognition of P. hippiana subsp. effusa, with the subspecies further subdivided into the two varieties recognized here. The varieties themselves intergrade; P. effusa var. ×coloradensis (Rydberg) Th. Wolf is available for the hybrid. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 9, p. 217. | FNA vol. 9, p. 162. | ||||
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Pensylvanicae | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Leucophyllae | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | P. pensylvanica var. bipinnatifida | P. hippiana subsp. effusa, P. hippiana var. effusa | ||||
Name authority | Douglas: in W. J. Hooker, Fl. Bor.-Amer. 1: 188. (1832) | Douglas ex Lehmann: Nov. Stirp. Pug. 2: 8. (1830) | ||||
Web links |