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

72a. Potentilla crebridens Juzepczuk subsp. hemicryophila Jurtzev in A. I. Tolmatchew, Fl. Arct. URSS. 9(1): 318. 1984.

Potentilla matsuokana Makino subsp. hemicryophila (Jurtzev) Soják

Plants ± tufted. Caudex branches slender to stout, not columnar, not sheathed with marcescent whole leaves. Stems ascending to erect, 0.8–2 dm, lengths 2–3(–4) times basal leaves. Basal leaves 3–8 cm; petiole 0.5–5 cm, cottony hairs usually dense, sometimes sparse, other hair types and glands absent or obscured; leaflets ± overlapping, central obovate, 0.6–2 × 0.5–1.2 cm, subsessile, base cuneate, margins slightly revolute, distal 3/4 to nearly whole length incised 1/4–1/3(–1/2) to midvein, teeth (3–)5–8(–12) per side, approximate, surfaces ± to strongly dissimilar, abaxial ± white, long hairs 0.7–1.2 mm, cottony-crisped hairs usually dense, adaxial green to grayish green, long hairs sparse to abundant, short and/or crisped hairs sparse to abundant. Cauline leaves 0–1. Inflorescences 1–6-flowered. Pedicels 1–1.5 cm in flower, to 3 cm in fruit. Flowers: epicalyx bractlets linear, 3–5 × 0.2–0.6 mm, usually less than 1/4 as wide as sepals, margins flat, red glands absent; hypanthium 4–4.5 mm diam.; sepals 5–6 mm, apex acute; petals 5–7 × 5–8 mm, slightly longer than sepals; filaments 1 mm, anthers 0.4 mm; carpels 25–30, apical hairs absent, styles columnar, not or ± papillate-swollen on less than proximal 1/5, 0.9–1.1 mm. Achenes 1.1 mm. 2n = 28 (Russian Far East).

Flowering summer. Dry alpine ridges and meadows, well-drained slopes, rocky outcrops, scree, on calcareous bedrock; 0–1500 m; Yukon; Alaska; Asia (Russian Far East, Siberia).

Nearly half of the Alaska and Yukon (Beringian) specimens previously assigned to Potentilla nivea belongs to P. crebridens subsp. hemicryophila, which is tetraploid; P. nivea is high polyploid. Intermediates were not seen, and the two species may be reproductively isolated by the ploidal difference. See B. A. Jurtzev (1984) for additional character differences.


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