Flora of the Canadian Arctic Archipelago
English: Egede's silverweed,
French: Potentille d'Egede.
Rosaceae, Rose family.
Published in Mem. Dept. Bot. Columbia Coll. 2: 158. 1898.
Type: Described fom Greenland: Holsteinborg area.
Synonymy. Potentilla egedii Wormskjold, Fl. Dan. 9, 27: 5, t. 1578. 1818.
Potentilla anserina L. subsp. egedii (Wormskjold) Hiitonem, Suomen Kasvio 449. 1933.
Argentina anserina (L.) Rydberg subsp. egedii (Wormskjold) Á. Löve and Ritchie, Canad. J. Bot. 44: 435. 1966.
Potentilla anserina L. subsp. groenlandica Tratt., Ros. Monogr. 4: 13. 1824.
Potentilla egedii Wormskjold var. groenlandica (Tratt.) Polunin, Rhodora 41: 90. 1939.
Vegetative morphology. Plants (1.5–)2–4(–10) cm high (in extreme environments to 30 cm high); perennial herbs; caespitose. Only fibrous roots present. Ground level or underground stems horizontal; stoloniferous; elongate; 3–6 mm wide. Caudex present (short and thick). Aerial stems stolon from which leaves arise; ascending, or prostrate; filiform (prostrate stems), or not filiform (ascending flowering stems). Leaves mainly basal and distributed along the stems (in basal tufts and as tufts at the nodes of the horizontal stems); alternate; dying annually and non-persistent. Stipules present; (2–)4–6 mm long; 1.5–2.5 mm wide; sheathing (united at the base); pink or reddish (hyaline to pale brown); glabrous; apex acute, or obtuse. Petioles (3–)5–12(–20) mm long (rarely to 60 mm); glabrous. Leaf blades compound. Blades (10–)15–20(–30) mm long (to 60 mm long Greenland specimens), (10–)15–25 mm wide (to 40 mm wide, Greenland specimens), veins palmate (leaflet veins pinnate). Blade adaxial surface glabrous. Blade abaxial surface glaucous, without sessile glands or glandular hairs, glabrous or hairy, hairs tomentose and short-silky (on midvein short-tomentose between veins), hairs sparse or moderately dense or very dense, hairs white, hairs straight or wavy, hairs appressed. Blade margins dentate, glabrous, with 3–6(–10) teeth on each side of the blade (rarely), with teeth toward the apex; degree of incision 20–50%; apices rounded. Leaflet arrangement pinnate (often with smaller leaflets between the main ones). Leaflets (5–)7–10(–12); 5–10(–15) mm long (in large plants up to 25 mm long); (2–)4–6(–10) mm wide (in large plants to 15 mm wide); obovate, or oblong; veins conspicuous. Apical leaflet base not distinctly stipitate.
Reproductive morphology. Flowering stems about as high as the leaves, or conspicuously taller than the leaves; without leaves. Flowers solitary. Flowers medium-sized. Sepals conventional. Epicalyx present. Epicalyx segments (1.8–)2–4 mm long. Epicalyx segments 0.5–1 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; 3–5(–6) mm wide; red (brownish). Calyx without sessile glands; hairy (sparsely). Calyx margins without cilia. Petals conventional; free; 5; yellow; without contrasting markings; obovate; unlobed; 0.5–10(–12) mm long; 4–8(–12) mm wide. Stamens 20–30; stamen filaments glabrous. Anthers yellow; ellipsoid, or sub-globose; 0.4–0.6 mm long. Ovary superior; carpels 15–25; apocarpous. Styles 1.2–1.8 mm long; straight; basal portion smooth. Ovules per ovary 1. Fruit with calyx persisting; dry; an aggregate of achenes; ovoid; green at maturity, or straw-coloured; 3–5 mm long; 5–8 mm wide (individual achenes 1.9–2.1 mm long; 1.1–1.3 mm wide, ovate, smooth); glabrous; surface appearing veinless; indehiscent.
Chromosome information. 2n = 28, or 35, or 42.
2n (4x) = 28. For the collective species. Murray and Kelso (1997, western Alaska, in the meeting zone between the two subspecies).
For subspecies egedii,
2n (4x) = 28. Erlandsson (1942b, northern Europe); Löve and Löve (1956, Iceland; 1982a, Arctic Canada, for 'groenlandica'); Jørgensen et al. (1958, Greenland); Sokolovskaya and Strelkova (1960, northern Russia); Rousi (1965, northern Norway); Löve and Ritchie (1966, northern Canada); Zhukova (1966, northeastern Asia); Johnson and Packer (1968, northwestern Alaska); Dawe and Murray, in Löve (1979, Alaska); Engelskjøn (1979, northern Norway); Zhukova and Petrovsky (1985b, northeastern Asia);
2n (5x) = 35. Erlandsson (1942b, northern Russia, northern Norway, as 'groenlandica');
2n (6x) = 42. Erlandsson (1942b, northern Norway, as 'groenlandica'). Supposed basic chromosome number of family 7.
Ploidy levels recorded 4x,.
Ecology and habitat. Substrates: imperfectly drained moist areas; silt, clay, sand (rarely); with low organic content; halophytic. This species is restricted to salt marshes, most often found growing with Carex subspathacea, Stellaria humifusa, and Puccinellia phryganodes throughout the circumpolar area.
It is probably an insect-pollinated outbreeder (i.e., sexual).
North American distribution. Nearly circumpolar but always absent from the northernmost, ice-bound or strongly ice-scoured coasts. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago limited. Rare. Low Arctic and coastal. Arctic islands: Baffin, Victoria.
Northern hemisphere distribution. Circumpolar (with a large gap in northern Asia, mainly American with amphi-Beringian and amphi-Atlantic extensions). Northern Iceland, Northern Fennoscandian, KaninPechora, Polar Ural Novaya Zemlya, Kharaulakh, West Chukotka, South Chukotka, East Chukotka, West Alaska, North Alaska Yukon, Central Canada, Labrador Hudson Bay, West Greenland, East Greenland.
General notes. Elven et al. (2003) suggested that if Dasiphora, Comarum and Sibbaldiopsis are recognised as separate genera, we also have to recognise Argentina, as it is equally well differentiated (Eriksson et al. 1998) [Pl. Syst. Evol. 211: 155–179].
Argentina anserina/egedii constitutes a widespread complex where A. anserina s.s. is the temperate part and A. egedii is the arctic-subarctic part (see Rousi 1965, Hultén 1971). Fertile intermediates are frequent in northwestern and northern Europe in seashore sites where A. anserina s.s. and A. egedii meet, even if they are partly ecologically separated. Argentina egedii is restricted to silty and clayey salt marshes, whereas A. anserina s.s. is more frequent on sandy and gravelly shores and especially in driftwalls. The entity described as A. egedii var. groenlandica (or Potentilla anserina var. groenlandica) is intermediate between A. egedii and A. anserina s.s. in some aspects but belongs mainly within the former. Its main distinguishing character seems to be the more or less hairy lower surface of leaves. It is concentrated in the southern parts of the range of A. egedii where it meets A. anserina s.s. At subspecies level, subsp. groenlandica has priority, at species level A. egedii.
The hybridisation and the 'intermediacy' of var. groenlandica are two reasons for treating A. anserina and A. egedii as major eco-geographic races, i.e., as two subspecies, instead of as species. In the material from the Arctic islands, all specimens from Victoria and about half of those from Baffin show some 'groenlandica' features (i.e., more or less hairy lower leaf surfaces). In these areas, there seems to be intra-population variation not worth taxonomic recognition. However, the indumentum variation is within the 'egedii' entity rather than a sign of intermediacy.
The taxon is a complicated case. In Alaska-Yukon, Hultén (1968b) divided the variation on two species and within A. (Potentilla) egedii on three subspecies - one with two varieties - all of which reach the arctic parts. One of the subspecies ('yukonensis') was later transferred by Hultén to A. (Potentilla) anserina. In northwestern Europe three entities have been recognised through time, A. (Potentilla) anserina and two races of A. (Potentilla) egedii. One of these - 'groenlandica' - is transitional in one feature (lower leaf surface indumentum) between the two species and exemplifies the problem in consistent separation of A. anserina and A. egedii.
As 'typical', the two are very different in several presumed independent characters and also differ ecologically. Intermediate habitats are rare, but where they occur, intermediate plants are very often found and there seems to be no barrier except the eco-geographical one. It would be very tempting to treat them as subspecies except that a more deviant race within the A. egedii affinity occurs in the Beringian area, namely 'pacifica' or 'grandis'. To be able reflect these two levels of differentiation we should perhaps accept two species. In any case, the 'groenlandica' plants should be included in A. egedii subsp. egedii as a synonym. The name is accepted in several standard sources, e.g., Hultén (1968b), Löve and Löve (1975, as A. anserina subsp. groenlandica), and Böcher et al. (1978). If the 'egedii' entity is considered a subspecies of A. argentina, the correct name is also subsp. groenlandica (see Soják 1969, Löve 1970).
Illustrations. • Habitat. Dominant plants in a "meadow" of yellow flowers. Greenland, Godhavn (Udkiggen). 15 July, 1960. CMN Photo library S78–486. Photograph by Mr. Raymond Wood. • Habitat. Plants growing on sandy beach, an unusual habitat for this species. Note red stolons and yellow flowers borne singly. N.W.T., Tuktoyaktuk. 22 July, 1981. J.M. Gillett 18753. • Habitat among rocks. Plants growing among rocks near water's edge. Nunavut, Baffin Island, Soper Lake, landing beach near Kimmirut. 2002. Aiken. No Voucher. • Plant habit. Plant with distinctive red stolons and pinnate leaves growing in a Puccinellia phryganodes meadow. Manitoba, Churchill, Beech Bay. 24 July, 2001. Aiken and Brysting 01–021. • Close-up of plant. Etiolated plants growing in a moist, grassy habitat. Note yellow flowers, and pinnate leaves. Manitoba, Churchill, Beech Bay. 24 July, 2001. Aiken and Brysting 01–021. • Plant habit. Plants growing on muddy beach. Leaves with five to seven, glabrous leaflets. Flowers borne singly. N.W.T., Tuktoyaktuk. 20 July, 1981. J.M. Gillett 18714. • Close-up of flower. Flower with sepals that are rounded on the tips and much shorter than the unlobed, yellow petals. N.W.T., Tuktoyaktuk. 22 July, 1981. J.M.Gillett 18753. • Close-up of plant. Plants showing flowers that have dropped their petals, leaving the calyx, epicalyx, and developing fruit. Aiken and Brysting 01–021. • Close-up of fruit. Note narrow green epicalyx segments, broader reddish green calyx segments, numerous brownish stamens with shrunken anthers. Note the deep red aggregate of developing achenes in the centre. Manitoba, Churchill, Beech Bay. 24 July, 2001. Aiken and Brysting 01–021. • 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..