Comarum palustre L.
Rosaceae, rose family.
Comarum palustre L. Sp. Pl. 502. 1753.
Potentilla palustris (L.) Scop.
Comarum arcticum Gand. Bull. Soc. Bot. France, 56: 533. 1909.
Vegetative morphology. Plants perennial herbs; 4–10(–18) cm high; caespitose. Taproot absent. Caudex absent. Ground-level or under-ground stems horizontal; rhizomatous; elongate; 2–4 mm wide. Aerial stems developed (as branches from a horizontal stem); aerial stems decumbent; aerial stems glabrous. Leaves distributed along the stems; alternate; compound; existing for a single season or less (petioles and stipules marcescent). Stipules present; scale-like; (10–)12–18(–25) mm long; (1–)1.5–3(–4) mm wide; not sheathing; pink or reddish. Stipules glabrous, or hairy. Stipules hairs short-silky (rarely with a few scattered hairs); apex acute. Petioles 15–23(–30) mm long (often much larger further south); hairy, or glabrescent; hairs short-silky, or hairs long-silky (about 0.5 mm long); hairs less than the diameter of the petiole. Petioles hairs appressed; straight; smooth. Blades 15–30 mm long (often much longer further south); 25–50 mm wide (often much wider further south). Blades veins palmate (leaflet veins pinnate). Blades adaxial surface glabrous. Blades abaxial surface glaucous; glabrescent, or hairy. Blades abaxial surface hairs sparse. Blades abaxial surface hairs short-silky (very short hairs). Blades abaxial surface hairs white, or translucent hairs; straight; appressed. Blade margins serrate; with non-glandular hairs (appressed, sometimes the only hairs on the blade); with teeth all around the blade, or toward the apex; degree of incision 20–25 %; with teeth on each side of the blade 3–10. Leaf apices rounded, or retuse. Leaflet arrangement pinnate (sometime appearing digitate, leaflets divergent). Leaflets 5(–7); 15–30 mm long (longer further south); 10–20 mm wide (broader further south); elliptic, or obovate. Leaflets veins conspicuous (on both surfaces). Apical leaflet base not distinctly stipitate.
Reproductive morphology. Flowering stems present. Flowering stems with leaves (little different in size from the basal leaves); hairy (only in distal part). Flowering stem hairs short-silky, or pilose; simple and glandular; shorter than the diameter of the flowering stem; white or translucent. Flowers solitary (in the northern plants), or in inflorescences (further south). Inflorescence cymose; axillary; diffuse; elongating as the fruit matures. Pedicels present. Flowers per inflorescence 1(–10) (one in the Arctic Archipelago plants, often 5–10 on more southern plants); large, more than 15 mm in diameter or length. Epicalyx present. Epicalyx segments 2–4 mm long; 0.5–1 mm wide; shorter than the calyx segments (much so); narrower than the calyx segments (very much so). Calyx sepals 5; free; (5–)7–12(–14) mm long; (3–)3.5–4.5(–5) mm wide. Calyx purple (brownish); accrescent; with sessile glands; hairy; hairs short-silky. Calyx hairs glandular; white or translucent. Petals free; 5; pink; without contrasting markings; elliptic (acute to acuminate); unlobed; (2.5–)3–6(–8) mm long; (1–)1.5–2.5(–3) mm wide. Stamens 15–25(–30); filaments glabrous. Anthers purple (dark); ellipsoid; 1–1.2 mm long. Gynoecia superior. Carpels apocarpous; 40–60. Styles 0.9–1.2 mm long. Styles straight; basal portion smooth. Stigmas receptive surface at the end of an otherwise unmodified style. Fruit with calyx persisting; dry; an aggregate of nutlets; ovoid; indehiscent. Fruit 8–12 mm long; 10–15 mm wide; brown (pale); glabrous; surface appearing veinless.
Chromosome information. 2n = 28, 35, 42 (frequently), 64 (?).
28 (4x). - Wulff (1937 central Europe); Ehrenberg (1945 Sweden);
Löve and Löve (1956 Iceland); Kartashova et al. (1974 Siberia).
35-36 (5x). - Lövkvist in Weimarck (1963 Sweden); Taylor
and Mulligan (1968 western Canada); Zhukova and Petrovsky (1977 north eastern
Asia, 2n = 36, probably aneuploid); Al-Bermani et al. (1993 western
Europe).
42 (6x). - Jørgensen et al. (1958 Greenland);
Sokolovskaya (1960b, 1963, 1965, 1970, 1972); Sokolovskaya and Strelkova (1960,
1962); Lövkvist in Weimarck (1963 Sweden); Löve and Löve (1965,
1982a arctic Canada, 1982c eastern Canada); Löve and Ritchie (1966 northern
Canada); Zhukova (1966, 1967a, 1969 north eastern Asia, 1980 southern Chukotka);
Knaben and Engelskjøn (1967 southern and northern Norway); Johnson and
Packer (1968 northwestern Alaska ); Laane (1969b Norway); Löve (1970a);
Asker (1971); Zhukova and Tikhonova (1971 Chukotka); Krogulevich (1976, 1978,
1984 northern and southern and northern Siberia); Zhukova and Petrovsky (1976
western Chukotka); Zhukova et al. (1977a north eastern Asia); Engelskjøn
(1979 Norway); Yurtsev and Zhukova (1982 northern Siberia); Lövkvist and
Hultgård (1999 southern and northern Sweden); Gervais (1997b, 1999 eastern
Canada). Numerous more southern counts.
56 (8x). - Laane and Lie
(1985 Norway).
60-62–64. (9&#;x&#;none) - Sokolovskaya and
Strelkova (1941 northern Russia, 2n = 62–64); Zhukova (1967 northe
eastern Asia, 2n = 60, probably aneuploid); Dempsey et al. (1994 W Europe,
2n = 64). Supposed basic chromosome number of family 7. Ploidy levels
recorded 4x, 5x, 6x, 9x(?).
Distribution. Northern hemisphere distribution: circumboreal; Greenland, Canada, United States, Eurasia. Boreal and low arctic. Range in the Canadian Arctic Archipelago limited. Rare. Arctic Islands: Baffin. A mainly boreal and low arctic species that only reaches the Arctic Islands at two known sites on Baffin Island. It is also found several places on the mainland adjacent to Victoria Island.
Ecology and habitat. Substrates: around the margins of ponds, marshes; aquatic, or imperfectly drained moist areas; acidic, or non-calcareous; sand, silt, clay, moss; with high organic content, or peat.
Notes. The choice between recognizing this as a species of Potentilla or placing it in its own genus Comarum is largely a matter of how widely or narrowly Potentilla should be circumscribed. If Comarum is split off, it also necessitates recognition of Anserina and Dasiphora as separate genera whereas an inclusion of these in Potentilla should be followed by an inclusion of, e.g., Fragaria and Sibbaldia. At present prefer to accept Comarum as a separate genus.
Illustrations. • Habitat. Plants growing in Carex aqualtils meadow. Manitoba, Churchill, Bird Cove, 23 July, 2001, Aiken and Brysting 01–013. • Close-up of plant. Centre flower bud has broad calyx segments folded around the opening flower and narrow, extended epicalyx segments. Manitoba, Churchill, Bird Cove, 23 July, 2001, Aiken and Brysting 01–013. • Close-up of flowers. Flowers with narrow green epicalyx segments, broad, apiculate, purplish calyx segements, much smaller red petals, alternate with the sepals, two whorls of deep red pre-anthesis anthers, and a brownish centre with developing carpels. Aiken and Brysting 01–013. • Close-up of flower. Flower approximately 1.5 cm in diameter, with narrow green epicalyx segments, broad, apiculate, dark red, purplish, calyx segements, much smaller red petals, alternate with the sepals, two whorls of deep red pre-anthesis anthers, and a brownish centre with developing carpels. Aiken and Brysting 01–013. • Close-up of inflorescence. Close-up of inflorescence, showing three flowers on long pedicels. Aiken and Brysting 01–013. • Close-up of plant. Comarum palustre close-up of plants. Mildred and Raymond R. Wood Photograph Collection, Photo by R. Wood, Kotzebue, Alaska, July 19, 1962. CMN Photo library S78–803. • Close-up of flower. Flower of Comarum palustre showing two rows of stamens, small pink petals and larger purple sepals. National Collection of Nature Photographs 64/192, Canadian Museum of Nature. • 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).
