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FNA | Family List | FNA Vol. 9 | Rosaceae | Potentilla

8m. Potentilla Linnaeus sect. Subjugae (Rydberg) A. Nelson in J. M. Coulter and A. Nelson, New Man. Bot. Rocky Mt. 255. 1909.

Barbara Ertter

Potentilla [unranked] Subjugae Rydberg, Bull. Torrey Bot. Club 23: 397. 1896

Perennials, ± tufted, not stoloniferous; taproots not fleshy-thickened; vestiture of long, crisped, and/or cottony hairs, glands sparse to common, sometimes red. Stems 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. Leaves: 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. Inflorescences (1–)2–20(–30)-flowered, usually cymose, open. Pedicels straight in fruit, 0.5–2(–3) cm, proximal ± longer than distal. Flowers 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. Achenes smooth.

Species 2 (2 in the flora): w North America.

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.

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.   34 Potentilla subjuga
+ 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.   35 Potentilla saximontana


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