Potentilla uniflora Ledeb.
Rosaceae, rose family.
Mem. Acad. Sci. St.-Petersb. 5: 543. 1815.
Type: Described from the Russian Far East, 'Terra Tschuktschorum ad sin. St. Lawrentii', leg. Eschscholtz, type possibly in LE.
Potentilla ledebouriana A.E. Porsild, Bot. Canol Road, 226. 1951.
Vegetative morphology. Plants perennial herbs; (3–)5–10(–15) cm high; caespitose; densely tufted, with a leaf crown and suberect lateral flowering branches. Taproot present. Caudex present (short, or rarely long, elongated caudex with dark brown to blackish leaf remains). Ground-level or under-ground stems vertical and often branched; 5–10 mm wide. Vegetative stem a small transition zone between roots and branches arising at ground-level. Leaves in a basal tuft; alternate; compound; existing for a single season or less, or marcescent. Stipules present; scale-like; (5–)8–10(–15) mm long; 1.5–3 mm wide; not sheathing; green (pinkish when fresh, reddish brown when marcescent). Stipules hairy. Stipules villous and hairs long-silky; glandular; apex acute. Petioles (3–)5–15(–25) mm long; with sessile glands (mostly hidden by hairs); hairy; villous, or hairs long-silky. Petioles hairs spreading; straight, wavy, and crispate; smooth. Blades (7–)10–15(–25) mm long; 15–25(–30) mm wide. Blades veins palmate (leaflet veins pinnate). Blades adaxial surface with sessile glands; hairy. Blades adaxial surface hairs villous, or long-silky; simple, unbranched; sparse, or moderately dense; white and translucent. Blades abaxial surface dull (when visible); hairy. Blades abaxial surface hairs very dense. Blades abaxial surface tomentose (between veins), or hairs long-silky (on veins). Blades abaxial surface hairs white, or translucent hairs; straight, or wavy; appressed (the tomentose hairs), or spreading (the pilose hairs). Blade margins dentate; with non-glandular hairs; with teeth all around the blade; degree of incision (25–)40–60(–80) %; with teeth on each side of the blade 2–3(–4) (rarely). Leaf apices obtuse, or rounded. Leaflet arrangement palmate. Leaflets 3; (7–)10–15(–22) mm long; (6–)8–10(–12) mm wide; obovate. Leaflets veins conspicuous. Apical leaflet base not distinctly stipitate.
Reproductive morphology. Plants bisexual, or agamospermic (possibly agamospermous). Flowering stems present. Flowering stems conspicuously taller than the leaves, or about as high as the leaves (rarely); with leaves; hairy. Flowering stem hairs tomentose and villous (sparsely); simple; shorter than the diameter of the flowering stem, or longer than the diameter of the flowering stem (rarely); white or translucent. Flowers solitary, or in inflorescences (rarely). Inflorescence cymose (if applicable); axillary (on caudex); diffuse. Pedicels present (if applicable). Flowers per inflorescence 1(–3); medium-sized, 5–15 mm in diameter or length, or large, more than 15 mm in diameter or length. Epicalyx present. Epicalyx segments (4–)5–6(–7) mm long; 1–2 mm wide; equal in length to the calyx segments (or slightly shorter or longer); narrower than the calyx segments, or equal in width to a calyx segments (rarely). Calyx sepals 5; free; 5–7(–8) mm long; 2–3 mm wide. Calyx green; accrescent; with sessile glands; hairy; pilose, or villous, or hairs long-silky. Calyx hairs white or translucent. Calyx margins without cilia. Petals free; 5; yellow; without contrasting markings; obovate; shallowly lobed; (6–)7–10(–11) mm long; (7–)8–11(–12) mm wide. Stamens 20–30 (numerous); filaments glabrous. Anthers yellow; ellipsoid, or triangular; 0.3–0.5 mm long. Gynoecia superior. Carpels apocarpous; 35–50. Styles 0.6–1 mm long. Styles straight; basal portion covered with short papillae, less than 0.1 mm high. Stigmas plate shaped, or capitate. Fruit sessile. Fruit with calyx persisting; dry; an aggregate of nutlets; ovoid; indehiscent. Fruit 1.4–1.8 mm long; 0.8–1.2 mm wide; green at maturity, or straw coloured; glabrous; surface venation reticulate, or appearing veinless.
Chromosome information. 2n = 28. 14 (2x). - Zhukova and
Petrovsky (1985b north and north eastern Asia; Sokolovskaya et al. (1985 north
eastern Asia, as P. vulcanicola).
28 (4x). - Mulligan
and Porsild (1969 Yukon, 1970 northwestern Canada); Zhukova and Petrovsky (1971
Wrangel Island, 1972, 1975 western Chukotka); Zhukova et al. (1973 north eastern
Asia); Zhukova and Tikhonova (1973 Chuk); Zhukova (1980 southern Chukotka);
Packer and Witkus (1982 western Canada); Zhukova and Petrovsky in Yurtsev (1984,
as P. subvahliana, counted on the holotype); Zhukova and Petrovsky (1985b
northern and north eastern Asia, as P. uniflora, P. subvahliana
and as P. vulcanicola).
42 (6x). - Sokolovskaya and Strelkova
(1960, as P. uniflora); Petrovsky and Zhukova (1981 Wrangel Island, as
P. uniflora subsp. subvillosa); Zhukova and Petrovsky (1985b north
and north eastern Asia). Supposed basic chromosome number of family 7. Ploidy
levels recorded 2x&4x&6x.
Distribution. Northern hemisphere distribution: amphi-Beringian; Canada, United States, Eurasia. Low arctic, or alpine. Range in the Canadian Arctic Archipelago limited. Rare. Arctic Islands: Banks, Victoria. ANorth Americaphi-Beringian species not previously recognized for the Arctic Islands. The material from Banks and Victoria fits well with mainland material east of Mackenzie and material from Mackenzie, Richardson, and British Mountains.
Ecology and habitat. Substrates: tundra, slopes (dry gravel hillsides), ridges, cliffs; dry; calcareous; rocks, gravel, sand; with low organic content. Habitats: Exposed ridges and heaths, more often on open wind-eroded patches than in fully closed vegetation. Probably confined to circumneutral to basic substrates in the Arctic.
Notes. See also notes for P.vahliana. Several specimens from Banks and Victoria Islands, previously included in P. vahliana, differ from that relatively common taxon in having a purely white indumentum, slightly more deeply dissected leaflets, and conspicuously in lacking an elongated caudex thickly covered by leaf remains. The specimens from Banks and Victoria Islands are inseparable morphologically from Continental P. uniflora. They have previously been overlooked, both in the islands and on the mainland coast east of Mackenzie River. They may be more widespread than indicated here.
Illustrations. • Plant in habitat. Plants in boulder field. Alaska: Alaska Range, Mt Healy. July 1998. Photographed by R.Elven. Voucher in HbO. • Close-up of plant. Flowering small tussock. Note leaflets with a few coarse teeth and strong venation. Alaska: Alaska Range, Donelly Dome. 12.07.1998. Photographed by H.H.Grundt. Voucher in HbO. • Close-up of plant. Small and compact plant with little underground caudex. Showing long underground branching tap-root, densely compact leaves, Right the base of a plant pressed so that the reddish brown stipules are showing. The short caudex is a difference from Potentilla vahliana with an elongated caudex. Leaf indumentum is white-silky as compated with the yellowish grey indumentum of P. vahliana. N.W.T., Victoria Island, Holman. CAN 485174. • Arctic Island distribution.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, L.J. Gillespie, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, A.K. Brysting and H. Solstad. 1999 onwards. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
