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scarlet cinquefoil, Thurber's cinquefoil

dwarf cinquefoil

Stems

(2–)3–7(–10) dm.

initially ascending to erect, soon becoming prostrate, flagelliform, not branched, eventually rooting at some nodes, (0.3–)0.5–12 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.

± 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.

Cauline leaves

stipules usually toothed, sometimes entire.

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.

Inflorescences

(4–)10–35-flowered.

solitary flowers at stolon nodes.

Pedicels

0.5–4 cm.

(1–)2–5(–9) 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.

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.

Achenes

1.5 mm, ± rugose.

1.2–1.4 mm, smooth.

Rootstocks

erect, stout, 0.5–2 cm.

2n

= 28.

Potentilla thurberi

Potentilla canadensis

Phenology Flowering late Mar–early Jun.
Habitat Dry flats and slopes in lawns, pastures, roadsides, cherty slopes, dry meadows, edges of oak and conifer woodlands, often on acidic soil
Elevation 0–1500 m (0–4900 ft)
Distribution
from FNA
AZ; NM; nw Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
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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[BONAP county map]
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.)

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.)

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. 134.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Rubrae Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Potentilla
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. 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. 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
Synonyms P. canadensis var. pumila, P. canadensis var. villosissima, P. caroliniana, P. pumila
Name authority A. Gray: Pl. Nov. Thurb., 318. (1854) Linnaeus: Sp. Pl. 1: 498. (1753)
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