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scarlet cinquefoil, Thurber's cinquefoil

Stems

(2–)3–7(–10) dm.

erect, 1–3 dm.

Basal leaves

palmate, (2–)4–15(–30) cm;

petiole (2–)3–10(–25) cm, long hairs sparse to common, spreading, 1–3.5 mm, weak, glands sparse to abundant, sometimes absent;

leaflets 5(–7), at tip of leaf axis, central one (1–)2–6(–8) × (0.5–)1–2.5(–4) cm, petiolules 0(–10) mm, distal 3/4 to whole margin incised 1/5–1/4 to midvein, teeth (4–)7–15(–19) per side (sometimes secondarily toothed), (1–)2–3(–5) mm, teeth apex acute to ± obtuse, surfaces slightly to strongly dissimilar, abaxial pale green to white, straight hairs sparse to abundant, often dense on veins, 0.5–3 mm, cottony hairs absent or sparse to dense, glands ± sparse or absent, sometimes obscured, adaxial green, straight hairs sparse to abundant, 0.2–1 mm, cottony hairs absent, glands ± sparse or absent.

pinnate, (4–)5–10(–14) cm;

petiole 3–7(–10) cm, long hairs abundant, subappresssed to appressed, 0.5–2 mm, ± weak, short hairs absent, crisped or cottony hairs absent or sparse, glands absent or sparse;

leaflets 2–3 per side, on distal 1/3–1/2 of leaf axis, separate, terminal ones elliptic to obovate, (1.8–)2–2.5(–3) × 0.8–1.3 cm, margins revolute, incised nearly to midvein, undivided medial blade 1–2 mm wide, teeth (4–)5–7 per side, linear, surfaces ± dissimilar, abaxial grayish to white, long hairs ± abundant especially on veins, 1–1.5 mm, weak, short hairs absent, crisped hairs abundant to dense, glands absent or obscured, adaxial greenish gray, long hairs common, appressed, 0.5–1 mm, short hairs absent, crisped hairs absent or sparse, glands absent or obscured.

Cauline leaves

stipules usually toothed, sometimes entire.

1–2.

Inflorescences

(4–)10–35-flowered.

2–5-flowered, very open.

Pedicels

0.5–4 cm.

2–4 cm.

Flowers

epicalyx bractlets narrowly to broadly lanceolate-elliptic (rarely toothed or lobed), 4–9(–14) × (1–)1.5–2 mm;

sepals 4–10(–15) mm, apex acute to acuminate;

petals ± dark reddish throughout, (3.5–)6–10 × 6–10 mm;

filaments 1.5–3 mm, anthers 0.8–1 mm;

carpels 30–70, styles 2.5–3.5 mm.

epicalyx bractlets narrowly elliptic to linear, 3–4 × 0.5–0.8(–1) mm, lengths 2/3–3/4 times sepals, margins flat;

hypanthium 2.5–3 mm diam.;

sepals 3.5–5 mm, apex subacute, abaxial surfaces: venation indistinct, glands sparse to common, often obscured;

petals yellow, 7.5–10(–10.5) × 7.5–9(–10) mm, much exceeding sepals;

filaments 1–2 mm, anthers 0.5–0.7 mm;

carpels 50–60, styles papillate-swollen at very base, if at all, 0.8–0.9 mm.

Achenes

1.5 mm, ± rugose.

1.4–1.6 mm, smooth to faintly rugose.

2n

= 28 (14, 42, 56) (Russian Far East).

Potentilla thurberi

Potentilla anachoretica

Phenology Flowering summer.
Habitat Dry ridges, rocky outcrops, south-facing slopes, mainly on basic substrates
Elevation 500 m (1600 ft)
Distribution
from FNA
AZ; NM; nw Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; e Asia (Russian Far East)
Discussion

Varieties 2 (2 in the flora).

The abaxially white-cottony leaflets of var. atrorubens usually make it easily distinguished from var. thurberi, which lacks cottony hairs and is usually less hairy in general. The two varieties sometimes occur together and intermediates between the extremes are common.

The degree of glandularity and the lengths of the central leaflets are greater in the southern populations of both varieties. The glands are less widely distributed on the plants northward and are fewer in northern Arizona and New Mexico. Leaflets are shorter and broader north of Graham County, Arizona, and Otero County, New Mexico.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Potentilla anachoretica is isolated in sect. Pensylvanicae. B. A. Jurtzev (1993, pers. comm.) claimed indirect support for the presence of P. anachoretica in Alaska and Yukon by the presence of three hybrid species presumably involving P. anachoretica in their parentage: P. borealis Soják, P. murrayi Jurtzev, and P. petrovskyi Soják (sect. Rubricaules; discussed by B. Ertter et al. 2013). Potentilla anachoretica is confirmed from at least two sites in Brooks Range, northern Alaska.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Leaflets pale green abaxially, cottony hairs absent.
var. thurberi
1. Leaflets ± white to white abaxially, cottony hairs sparse to dense.
var. atrorubens
Source FNA vol. 9, p. 149. FNA vol. 9, p. 218.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Rubrae Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Pensylvanicae
Sibling taxa
P. albiflora, P. ambigens, P. anachoretica, P. angelliae, P. anglica, P. anserina, P. arenosa, P. argentea, P. arizonica, P. basaltica, P. bicrenata, P. biennis, P. biflora, P. bimundorum, P. bipinnatifida, P. brevifolia, P. breweri, P. bruceae, P. brunnescens, P. canadensis, P. concinna, P. cottamii, P. crantzii, P. crebridens, P. crinita, P. cristae, P. demotica, P. drummondii, P. effusa, P. elegans, P. erecta, P. flabellifolia, P. fragiformis, P. furcata, P. glaucophylla, P. gracilis, P. grayi, P. hickmanii, P. hippiana, P. holmgrenii, P. hookeriana, P. hyparctica, P. inclinata, P. intermedia, P. jepsonii, P. johnstonii, P. lasiodonta, P. litoralis, P. macounii, P. millefolia, P. modesta, P. morefieldii, P. multijuga, P. multisecta, P. nana, P. newberryi, P. nivea, P. norvegica, P. ovina, P. paucijuga, P. pedersenii, P. pensylvanica, P. plattensis, P. pseudosericea, P. pulchella, P. pulcherrima, P. recta, P. reptans, P. rhyolitica, P. rimicola, P. rivalis, P. robbinsiana, P. rubella, P. rubricaulis, P. sanguinea, P. saximontana, P. sierrae-blancae, P. simplex, P. sterilis, P. stipularis, P. subgorodkovii, P. subjuga, P. subvahliana, P. subviscosa, P. supina, P. thuringiaca, P. tikhomirovii, P. townsendii, P. uliginosa, P. uschakovii, P. vahliana, P. verna, P. versicolor, P. villosa, P. villosula, P. vulcanicola, P. wheeleri
P. albiflora, P. ambigens, P. angelliae, P. anglica, P. anserina, P. arenosa, P. argentea, P. arizonica, P. basaltica, P. bicrenata, P. biennis, P. biflora, P. bimundorum, P. bipinnatifida, P. brevifolia, P. breweri, P. bruceae, P. brunnescens, P. canadensis, P. concinna, P. cottamii, P. crantzii, P. crebridens, P. crinita, P. cristae, P. demotica, P. drummondii, P. effusa, P. elegans, P. erecta, P. flabellifolia, P. fragiformis, P. furcata, P. glaucophylla, P. gracilis, P. grayi, P. hickmanii, P. hippiana, P. holmgrenii, P. hookeriana, P. hyparctica, P. inclinata, P. intermedia, P. jepsonii, P. johnstonii, P. lasiodonta, P. litoralis, P. macounii, P. millefolia, P. modesta, P. morefieldii, P. multijuga, P. multisecta, P. nana, P. newberryi, P. nivea, P. norvegica, P. ovina, P. paucijuga, P. pedersenii, P. pensylvanica, P. plattensis, P. pseudosericea, P. pulchella, P. pulcherrima, P. recta, P. reptans, P. rhyolitica, P. rimicola, P. rivalis, P. robbinsiana, P. rubella, P. rubricaulis, P. sanguinea, P. saximontana, P. sierrae-blancae, P. simplex, P. sterilis, P. stipularis, P. subgorodkovii, P. subjuga, P. subvahliana, P. subviscosa, P. supina, P. thurberi, P. thuringiaca, P. tikhomirovii, P. townsendii, P. uliginosa, P. uschakovii, P. vahliana, P. verna, P. versicolor, P. villosa, P. villosula, P. vulcanicola, P. wheeleri
Subordinate taxa
P. thurberi var. atrorubens, P. thurberi var. thurberi
Name authority A. Gray: Pl. Nov. Thurb., 318. (1854) Soják: Preslia 46: 70, fig. [p. 71]. (1974)
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