Potentilla sect. Subjugae
Potentilla saximontana
Rocky Mountains cinquefoil
ascending to nearly erect, not flagelliform, not rooting at nodes, lateral to persistent basal rosettes, (0.2–)0.4–2.5(–3.5) dm, lengths 2–3 times basal leaves.
(0.2–)0.4–1(–1.5) dm.
basal not 2-ranked;
cauline 0–3;
primary leaves palmate with additional lateral pairs to pinnate (with distal leaflets distinct), (1–)1.5–10(–14) cm;
petiole: long hairs spreading to tightly appressed, weak to stiff, glands absent or sparse;
leaflets 5–7(–9), on distal 1/10–1/3(–1/2) of leaf axis, strongly overlapping or not, oblanceolate-oblong to obovate, margins scarcely to ± revolute, ± whole length evenly incised 1/2–3/4 to midvein, teeth 2–9 per side, surfaces ± to strongly dissimilar, abaxial white to grayish green, cottony hairs sparse to dense, adaxial green to grayish, not glaucous, long hairs ± stiff.
subpalmate to pinnate, (1–)1.5–4(–7) cm;
petiole 0.5–2(–4) cm, vestiture not or scarcely seasonally dimorphic, long hairs abundant to dense, appressed to spreading, 1–1.5(–2) mm, weak to ± stiff, cottony hairs usually absent, crisped hairs absent or sparse, glands sparse;
leaflets 3 at tip of leaf axis plus 1–2(–3) additional pairs separated from tip by 1–5 mm, on distal 1/10–1/3 of leaf axis, largest leaflets obovate to oblanceolate, 0.5–1.5 × 0.3–1.2 cm, ± whole margin incised 1/2–3/4 to midvein, teeth 2–4(–5) per side, separate to overlapping, 1–4 mm, surfaces ± dissimilar, abaxial grayish green to white, straight hairs abundant, 1–1.5 mm, cottony and crisped hairs sparse to dense, rarely absent, glands sparse or obscured, adaxial green to grayish, straight hairs sparse to abundant, 1–2 mm, cottony hairs absent or rarely sparse, crisped hairs absent or sparse, glands ± sparse.
0–1(–2).
(1–)2–20(–30)-flowered, usually cymose, open.
(1–)2–5(–10)-flowered.
straight in fruit, 0.5–2(–3) cm, proximal ± longer than distal.
0.5–1.5 cm (proximal to 2.5 cm).
5-merous;
hypanthium 3–5 mm diam.;
petals yellow, ± obcordate, 4–8 mm, equal to or longer than sepals, apex retuse;
stamens ca. 20;
styles subapical, filiform to filiform-tapered or filiform-columnar, papillate-swollen in proximal less than 1/5 if at all, 0.8–2 mm.
epicalyx bractlets ± ovate-elliptic, 2–4 × 1–1.5 mm;
sepals 3.5–5 mm, apex bluntly acute;
petals 4–6(–8) × 4–7 mm;
filaments 0.5–2 mm, anthers 0.5 mm;
carpels 10–20+, styles columnar-filiform, papillate-swollen at base, if at all, 0.8–1.5 mm.
smooth.
1.5 mm.
Potentilla sect. Subjugae
Potentilla saximontana
Species 2 (2 in the flora).
Section Subjugae is used primarily to accommodate the unique leaf dissection and vestiture of Potentilla subjuga, which commonly has five palmately arranged leaflets and one, sometimes two, additional pairs of lateral leaflets. Sometimes leaves are simply pinnate with only three terminal leaflets, and sufficient intergradation occurs with P. saximontana that it is also included in the section. This circumscription coincides with the initial concept of Rydberg and Nelson and contrasts with that of B. C. Johnston (1980, 1985).
Section Subjugae is restricted to subalpine and alpine habitats in the Rocky Mountains and adjacent ranges of western North America centered in Colorado. Variation within the section is complex and poorly understood, such that the two species treated here represent only the best expressed extremes with existing names. Other named components of uncertain placement include Potentilla lupina Rydberg, P. minutifolia Rydberg, P. rubricaulis var. nana Clements & E. G. Clements, P. rubripes Rydberg [= P. concinna var. rubripes (Rydberg) C. L. Hitchcock], and P. tenerrima Rydberg.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Potentilla saximontana is a small plant of very high elevations in the mountains of Colorado, the La Sal and Uinta mountains of Utah, and the Absaroka and Beartooth mountains of Wyoming and Montana. Although sometimes confused with P. rubricaulis (for example, W. A. Weber and R. C. Wittman 1996), the subpinnate leaves, open few-flowered inflorescences, and columnar-filiform styles make P. saximontana a distinct species.
The lectotype of Potentilla nivea Linnaeus var. dissecta S. Watson [= P. saximontana var. dissecta (S. Watson) Soják] has been tentatively included in P. saximontana (B. Ertter 2008), but P. saximontana is not otherwise known from the Canadian Rockies. See B. Ertter et al. (2013) for additional discussion.
The combination Potentilla rubripes Rydberg var. saximontana (Rydberg) Th. Wolf is incorrect, in that P. saximontana is the older name.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaflets at tip of leaf axis (3–)5; styles 1.5–2 mm; stems (0.8–)1–2.5(–3.5) dm; inflorescences 3–20(–30)-flowered. | P. subjuga |
1. Leaflets at tip of leaf axis 3; styles 0.8–1.5 mm; stems (0.2–)0.4–1(–1.5) dm; inflorescences (1–)2–5(–10)-flowered. | P. saximontana |
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