Flora of the Canadian Arctic Archipelago

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S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, L.J. Gillespie, A.K. Brysting, H. Solstad, and J.G. Harris

Potentilla rubricaulis Lehm. aggregate

Rosaceae, Rose family.

Published in Nov. Stirp. Pūg. 2: 11. 1830

Type: Described from Canada: NWT, Mackenzie District: "about Bear Lake, in lat. 66°. leg. Dr. Richardson", i.e., the Great Bear Lake area, probably close to Fort Franklin. Holotype: K?

Synonymy. Potentilla pedersenii Rydberg, N. Amer. Fl. 22: 332. 1908.(Described from W Greenland: Disko Island, Vaigat Assuk)

Vegetative morphology. Plants (5–)8–20(–35) cm high; perennial herbs; caespitose. Taproot present (stout). Ground level or underground stems vertical; 5–15 mm wide. Caudex present (short, very stout, sub-ligneous, freely branched and covered with the dark brown remains of old leaves). Aerial stems branching from a tap at or near ground level into two or more branches. Leaves mainly basal; alternate; dying annually and non-persistent and marcescent (petioles and stipules marcescent, blades shorter lived). Stipules present; (8–)10–15(–20) mm long; 1.5–3(–5) mm wide; not sheathing; green (often pinkish, reddish brown when marcescent); hairy; long-silky (often densely so); glandular; apex acuminate, or acute. Petioles (10–)25–40(–50) mm long; with sessile glands (mostly hidden by hairs); hairy; villous, or long-silky. Petiole hairs appressed and spreading; straight, wavy, and crispate (straight hairs dominant, wavy and crispate hairs scattered); smooth, or rough. Leaf blades compound. Blades (10–)15–20(–25) mm long, (12–)17–23(–28) mm wide, veins palmate (leaflet veins pinnate). Blade adaxial surface with sessile glands, hairy, hairs pilose or villous or long-silky, hairs simple, hairs moderately dense or dense, hairs white, or translucent. Blade abaxial surface dull, hairy, hairs tomentose (between veins) or long-silky (on veins), hairs very dense, hairs white, hairs straight or wavy, hairs appressed or spreading. Blade margins deeply divided or dentate (rarely), with non-glandular hairs (that are very long and tufted at the apex), with 3–5 teeth on each side of the blade, with teeth all around the blade; degree of incision 50–90%; apices rounded. Leaflet arrangement palmate, or digitate, or pinnate (rarely). Leaflets 3–5(–7); (10–)12–18(–35) mm long; (5–)8–12(–15) mm wide; elliptic, or obovate; veins conspicuous. Apical leaflet base not distinctly stipitate.

Reproductive morphology. Plants agamospermic (probably), or bisexual (possibly). Flowering stems conspicuously taller than the leaves; with leaves. Flowering stems hairy. Flowering stems villous and long-silky. Flowering stem hairs simple; shorter than the diameter of the flowering stem, or longer than the diameter of the flowering stem; white or translucent. Flowers in inflorescences, or solitary (rarely). Inflorescences cymose; diffuse. Pedicels present (usually). Flowers per inflorescence (1–)2–4(–8); medium-sized, or large. Sepals conventional. Epicalyx present. Epicalyx segments (3–)4–6(–8) mm long. Epicalyx segments 1.5–2(–3) mm wide. Epicalyx segments shorter than the calyx segments, or equal in length to the calyx segments. Epicalyx segments narrower than the calyx segments. Sepals 5; free; (1.5–)2–2.5(–3) mm long; (3–)4–5(–6) mm wide; green; accrescent. Calyx with sessile glands; hairy. Calyx hairs pilose, or long-silky; white or translucent. Calyx margins without cilia. Petals conventional; free; 5; yellow (a dark yellow); without contrasting markings; obovate; slightly lobed or undulating; (5–)6–11(–12) mm long; (7–)8–12(–14) mm wide. Stamens 20–30; stamen filaments glabrous. Anthers yellow; ellipsoid, or triangular; 0.4–0.8 mm long. Ovary superior; carpels 30–45; apocarpous. Styles 0.6–0.9 mm long; conical, or straight; basal portion smooth, or covered with short papillae, less than 0.1 mm high (shorter than in P. nivea and P. chamissonis). Ovules per ovary 1. Fruit sessile; with calyx persisting; dry; an aggregate of achenes; ovoid; green at maturity, or straw-coloured; 0.75–1 mm long; 0.4–0.8 mm wide; glabrous; surface appearing veinless; indehiscent.

Chromosome information. 2n = 42, or 48 (49?), or 56.

2n = 42. Jørgensen et al. (1958);

2n = 48 (49?) and 56. Dansereau and Steiner (1956). Supposed basic chromosome number of family 7.

Ploidy levels recorded 6x, 7x, 8x.

Ecology and habitat. Substrates: around the margins of ponds (rarely, e.g., DAO 343139), river terraces (dry), tundra, slopes, ridges, cliffs, dry meadows; dry, moderately well-drained areas; rocks, gravel, silt, till (sometimes found near talus slopes, e.g., DAO 182928, 509347a); with low organic content; calcareous, or nitrophilous. Similar to P. nivea but with a preference for calcareous substrates and more finely grained substrates, often on periodically damp or wet silt or clay flats.

North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut. Range in the Canadian Arctic Archipelago widespread. Common (in the west), uncommon (in the east). Arctic. Arctic islands: Baffin, Devon, Ellesmere, Axel Heiberg, Parry islands (Eglinton, Emerald, Melville, Prince Patrick), Banks, Victoria, Somerset, Southampton.

Northern hemisphere distribution. Amphi-Atlantic (broadly), or amphi-Beringian (broadly), or North American. Svalbard – Franz Joseph Land, Polar Ural – Novaya Zemlya, West Chukotka, Wrangel Island, South Chukotka, East Chukotka, West Alaska, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, Ellesmere Land – Peary Land, West Greenland, East Greenland.

General notes. What here is entered as a P. rubricaulis aggregate is a possibly artificial group of plants that have mainly three features in common: leaves digitate (more than three leaflets attached at about the same point) or semipinnate (more than three leaflets attached along a very short axis); an often silky indumentum of long, often shiny hairs on both leaf surfaces (and on other parts); and multiflowered stems. They are interpreted by J. Soják and B. Yurtsev (personal communication) as probably agamospermic derivatives from hybrids between several species of sect. Niveae (both the P. nivea group and the P. uniflora group) and at least two species of sect. Multifidae (P. anachoretica, P. pulchella, perhaps also P. bimundorum in the case of P. rubricaulis s. str.).

The hypotheses of Soják and Yurtsev may well be true as to the origin of the aggregate. It still leaves the question whether it is feasible (and worthwhile) to try to classify such agamic complexes. In this aggregate, some of the entities are comparatively widespread and may be locally common. They cannot be ignored. However, they often vary morphologically from island to island, and sometimes from site to site. It is evident that their evolutionary background is diverse and includes several parental species. The choice is between a collective treatment and a treatment as several species. The former option is chosen here, as the data needed for a more detailed taxonomic treatment still are absent. Numerous taxa have been described from northeastern Asia and Alaska (and one from the European North Atlantic), but it is uncertain or even improbable whether these are the relevant ones in northern Canada and Greenland. The variation in northern Canada is much too large to fit well into the two taxa described from this area. This is a matter for further studies.

For North America and Greenland, the following seven entities have been proposed. The suggested origins are indicated.

Potentilla rubricaulis Lehm. Perhaps originating from P. bimundorum Soják (Multifidae) and P. arenosa s.l. (Niveae). This entity, described from Mackenzie District, occurs north to Liverpool Bay and Cape Dalhousie, but is unlikely to occur in the archipelago islands.

Potentilla pedersenii Rydberg Probably originating from P. pulchella R. Br. (Multifidae) and a species of sect. Niveae. This entity, described from Greenland, is probably a name that is relevant for at least some plants from the northeastern islands.

Potentilla borealis Soják Probably originating from P. anachoretica Soják (Multifidae) and P. arenosa s. str. (Niveae). This entity, described from West Chukotka, has been reported from Alaska and may occur in the western archipelago islands.

Potentilla petrovskyi Soják Probably originating from P. anachoretica Soják (Multifidae) and P. nivea s. lat. (Niveae, most probably subsp. hemicryophila or P. crebridens). This entity, described from South Chukotka, has also been reported from Alaska and may occur in the western archipelago islands.

Potentilla tschaunensis Juz. ex Jurtz. This entity probably has the same general origin. It is described from West Chukotka, reported from Alaska, and may occur in the western archipelago islands.

Potentilla murrayi Jurtz. Probably originating from P. anachoretica Soják (Multifidae) and a species of the P. uniflora group (Niveae, Yurtsev proposed P. subvahliana Jurtz. as the parent). This entity, described from Brooks Range in northern Alaska, might be relevant in northwestern Canada.

Potentilla insularis Soják Proposed by Soják as originating from P. lyngei Jurtz. and Soják (Multifidae) and P. arenosa (Trautv.) Juz. subsp. chamissonis (Hultén). This origin has been disputed (Hansen et al. 2000, Hamre 2000), because P. lyngei is absent from the area where it occurs and because the Multifidae species that is present (P. pulchella) does not seem to be involved. It is reported from Svalbard and much more doubtfully from Greenland. As it certainly is closely related to, and probably derived from, P. arenosa subsp. chamissonis, it may well occur in northern Canada.

Illustrations. • Habitat. Single plants in a typical habitat of dry, calcareous, sandy or loamy soils. N.W.T., Banks Island, Sachs River delta across from Sachs Harbour. 28 July, 1981. J.M. Gillett 18897. • Habitat. Large plant (arrow) growing on tributary of river to McCormick Inlet. N.W.T., Melville Island. August, 2000. L.J. Gillespie 6946 and L.L. Consaul. • Close-up of plant. Plant in late stages of flowering. Note flower erect and developing fruits prostrate on the tundra. Melvillle Island, McCormick Inlet. August, 2000. L.J. Gillespie 6946 and L.L. Consaul. • Close-up of flower. Close-up of flower. Melville Island, McCormick Inlet. 2 August, 2000. L.J. Gillespie 6946 and L.L. Consaul. • Close-up of leaf. Close-up of underside of leaf. Melville Island, McCormick Inlet. 2 August, 2000. L.J. Gillespie 6946 and L.L. Consaul. • Arctic Island Distribution.


This publication is available on the internet (posted May 2011) and on CD-ROM (published in 2007). These versions are identical in content, except that the errata page for CD-ROM is accessible on the main index page of the web version.

Recommended citation for the web-based version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. NRC Research Press, National Research Council of Canada, Ottawa. http://nature.ca/aaflora/data, accessed on DATE.

Recommended citation for the CD-ROM version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. [CD-ROM] NRC Research Press, National Research Council of Canada, Ottawa.

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