Flora of the Canadian Arctic Archipelago


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

Saxifraga cespitosa L.

English: Tufted saxifrage, tufted alpine saxifrage,

French: Saxifrage cespiteuse.

Saxifragaceae, Saxifrage family.

Published in Sp. Pl. 404. 1753.

Type: Selected by Webb, Bot. J. Linn. Soc. 95: 264–265. 1987. Lectotype: LINN 575.57.

Synonymy. Muscaria cespitosa (L.) Haw., Saxifr. Enum. 37. 1821.

Muscaria sileniflora (Sternb.) Small, N. Amer. Fl. 22, 2: 130. 1905.

Saxifraga groenlandica L., Sp. Pl. 404. 1753.

Saxifraga. sileniflora Sternb. ex Cham., Linnaea 6: 55. 1821.

Saxifraga. cespitosa L. subsp. sileniflora (Sternb.) Hultén, Fl. Aleut. Isl. 210. 1937.

Saxifraga uniflora R. Br., Chloris Melvill. 16. 1823.

Saxifraga cespitosa L. f. uniflora (R. Br.) Engler and Irmsch., in Engler. Das Pflanzenreich 67 (IV, 117), 371 1916.

Saxifraga cespitosa L. subsp. uniflora (R. Br.) A.E. Porsild, Natl. Mus. Canada Bull. 135, Biol. Ser. 45: 135. 1955.

Muscaria monticola Small, N. Amer. Fl. 22, 2: 130 1905.

Saxifraga monticola (Small) Fedde, Just's Bot. Jahresber. 33: 613. 1906.

Saxifraga cespitosa L. subsp. monticola (Small) A.E.Porsild, Bull. Natl. Mus. Canada 216: 39. 1966.

Saxifraga cespitosa L. subsp. exaratioides (Simmons) Engl. and Irmsch., Pflanzenreich IV,117, 1, 67: 375. 1916.

Saxifraga cespitosa subsp. eucespitosa f. laxiuscula Engl. Irmsch., in Engl., Pflanzenreich IV, 117: 371. 1916.

Saxifraga. cespitosa L. subsp. laxiuscula (Engl. and Irmsch.) Á. Löve and D. Löve, Bot. Not. 114: 53. 1961.

Saxifraga aurea (Hada) Rönning, nom. inval., Svalbard. Fl., ed. 3, 115. 1996.

Vegetative morphology. Plants 3.5–20 cm high; perennial herbs; caespitose; never vegetatively proliferating by bulbils on stems or leaves, in inflorescences, from gemmiphores and gemmae, or by fragmentation (but vigorous new shoots occur in the axils of the upper-leaves). Taproot present (persisting for a long time; adventitious roots weak). Ground level or underground stems vertical; elongate (rarely), or compact (usually). Horizontal stems at ground level, branching extensively to shape plant habit as cushions. Caudex present. Aerial stems erect (usually). Leaves mainly basal, or basal in a rosette; erect; alternate; persistent (on the lower stem only and persisting several years). Petioles 7–12 mm long (to 35 mm long in etiolated plants); hairy (with glandular hairs on the margins). Leaf blades simple. Leaf blade bases truncate. Blades 5–15 mm long (usually, to 25 cm, CAN550018), 3–11 mm wide, spatulate (or not applicable), flat, with inconspicuous veins. Blade adaxial surface hairy, hairs glandular. Blade abaxial surface glabrous. Blades lobed. Blade margins deeply divided (into 3, occasionally 5 strap-like, lobes, rounded at the apex), with glandular hairs (sparse, usually near base). Hydathodes present and conspicuous (at the apex of each leaf lobe), or absent (not readily visible).

Reproductive morphology. Flowering stems two or more per plant; with leaves. Flowering stems hairy. Flowering stems pubescent (with glandular hairs). Flowering stem hairs simple; shorter than the diameter of the flowering stem; white or translucent, or yellow; glandular hairs present (seen at 10–40×). Flowers solitary, or in inflorescences. Inflorescences racemose, or cymose; 0–2 cm long. Pedicels present, or absent; with sessile glands. Flowers per inflorescence 1–3 (usually, to 4 CAN 204618); medium-sized (sometimes with a faint scent). Sepals conventional; 5; free; 1–1.5 mm long; 2.5–3 mm wide; green. Calyx hairy. Calyx hairs glandular; white or translucent. Petals conventional; free; 5; white, or yellow (pale cream, greenish yellow); with contrasting markings (three yellowish green vertical stripes); obovate; unlobed; 4–7(–15) mm long; 2.5–3 mm wide. Stamens 10; stamen filaments glabrous. Anthers yellow; sub-globose; 0.4–0.5 mm long. Nectaries present. Receptacle (3.5–)4–6(–7) mm high. Ovary partly inferior; carpels 2; partly fused. Ovaries glabrous. Placentation axile. Ovules per ovary 20–50 (approx.). Fruit with calyx persisting; dry; a capsule; elongate-cylindrical (obdeltoid, apex truncate); brown; 7–10 mm long; 5–7 mm wide; hairy; dehiscent; splitting to the base into separate segments. Seeds 20–50 (approx.); 0.8–1.2 mm long; brown; surfaces smooth and winged (on one side).

Chromosome information. 2n = 78, or 80.

(2n) = 78. Parker (1982, western Europe);

(2n) (10x) = 80. Böcher (1938a, 2n = about 80); Flovik (1940, Svalbard); Harmsen, in Löve and Löve (1948); Böcher and Larsen (1950, Greenland, by Löve and Löve 1975, entered as subsp. laxiuscula); Löve and Löve (1951, 1956, Iceland, both by Löve and Löve 1975, entered as subsp. caespitosa; 1961b, northeastern USA, both by Löve and Löve 1975, entered as subsp. laxiuscula; 1982a, Arctic Canada, as Muscaria cespitosa subsp. exaratoides); Holmen (1952, Greenland); Jørgensen et al. (1958, Greenland, by Löve and Löve 1975 entered as subsp. laxiuscula); Sokolovskaya (1958); Sokolovskaya and Strelkova (1960); Mosquin and Hayley (1966, northern Canada, 2n = about 80); Zhukova (1968, northeastern Asia); Johnson and Packer (1968, northwestern Alaska, by Löve and Löve 1975, entered as subsp. sileniflora); Packer and McPherson (1974, northern Alaska, 2n = about 80, by Löve and Löve 1975, entered as subsp. sileniflora); Petrovsky and Zhukova (1981, Wrangel Island); Zhukova and Petrovsky (1987a, northern Asia).

Ploidy levels recorded 10x.

Taxon as an environmental indicator. This is a colonising species that has a wide range of environmental tolerance, but is unable to withstand competition, so that it is rarely found in closed communities. The morphological expression of plants is a useful indication of favourable or adverse growing conditions in a habitat. Polunin (1940) indicated that the northernmost record was Cape Black, 83°01'N, on the north coast of Greenland. It has since been collected in Canada on Ward Hunt Island at 83°03'N (Canada).

Ecology and habitat. Substrates: rocks; calcareous, or nitrophilous, or circum-neutral. Warming (1909) noted that in the flowers, nectar is secreted abundantly from the yellowish green glistening base of the gynoecium. He had observed the species in Greenland to be slightly protandrous. In a recently opened flower, all the stamens are erect or bent somewhat outwards to lie against the petals; but gradually the stamens begin to bend inwards so that the open anthers are placed above the still unripe stigmas. Later the stamens bend backwards, but before they do so the styles have spread outwards and the stigmas have become ripe, with the results that self-pollination may occur.

Warming (1909) found that the terminal flower in the inflorescence often develops differently from the other flowers. Its styles develop quickly and bend outwards, and the stigmas become highly papillose while the anthers are still entirely closed. These anthers are smaller, never open, and appear to have abnormal pollen, so that the flower is regarded as pistillate with large staminodes.

Polunin (1940) reported that this species flowers and sets ripe seed in abundance, even in the most northerly and exposed habitats. It is dispersed by wind shaking the seeds out of the capsules.

North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago widespread. Common. Arctic and alpine. Arctic islands: Baffin (Bylot, Coats, Digges, Mill, Nottingham, Prince Charles, Resolution, Sailsbury), Devon, Ellesmere, Axel Heiberg, Parry islands (Bathurst, Cameron, Eglington, Emerald, Helena, Mackenzie King, Melville), Cornwallis, Banks, Victoria, Prince of Wales, Somerset, King William (Amund Ringes, Ellef Ringes, Loughead, and Meighen, Boothia and Melville peninsulas).

Northern hemisphere distribution. Circumpolar, or circumboreal (arctic-alpine). Northern Iceland, Northern Fennoscandian, Kanin–Pechora, Svalbard – Franz Joseph Land, Polar Ural – Novaya Zemlya, Yamal–Gydan, Taimyr – Severnaya Zemlya, Anabar–Olenyok, Kharaulakh, Yana–Kolyma, 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. This is a circumpolar arctic-alpine species that is complicated and poorly studied. "Some forms have been described as species. The majority of botanists now regard S. cespitosa as a polymorphic species with several morphologically poorly differentiated races" (Zhmylev, in Elven et al. (2003)).

This polymorphous species varies greatly in form and size with local conditions. It forms loose stands with branched inflorescences growing 20 cm or more high in sheltered rocky or manured places and dense cushions bearing a few unifloral axes, sometimes only 2 or 3 cm high in unfavourable situations. Distinct taxa have been recognised based on this variation. We have not maintained the three that Porsild (1957) and Porsild and Cody (1980) recognised as occurring in northern Canada. They are as follows:

1. subsp. cespitosa (= subsp. eucespitosa Engl. and Irmsch. an invalid name). Flowers relatively large, 8–10 mm wide, usually 3, rarely 1 or 2, Amphi-Atlantic subarctic.

2. subsp. uniflora (R. Br.)Porsild. Flowers smaller, 4–7 mm wide, mostly solitary, calyx purplish black, circumpolar with large gaps.

3. subsp. exaratoides (Simm) Engl. and Irmsch. emend. Porsild. Flowers mostly 3, calyx greenish purple, endemic to Paleozoic parts of Hudson Bay region, north to Ellesmere Island (Porsild 1955).

Polunin (1940, p. 257) observed that this is "one of the commonest and hardiest of arctic plants, having such a wide range of tolerance to most environmental conditions that it can grow in almost any habitat. However, it prefers open clayey plains and sandy or gravelly seashores or exposed ridges, being unable to withstand much competition .... and hence found only occasionally in closed communities".

Whittaker (1993), studying plant population patterns in the Storbreen glacier foreland succession, 61°35'N, 8°E, found that S. cespitosa and Arabis alpina L. are visually the most characteristic forbes of the youngest ground. Both species peaked in local frequency within 30 years of deglaciation in sites close to the glacier snout and subject to severe physical disturbance by periglacial activity. They had virtually disappeared from the vegetation within approximately 50 years.

Crawford et al. (1994) found a uniquely high level of anoxic tolerance in Spitsbergen populations of this species and S. cernua, S. foliolosa, S. hieracifolia, and S. oppositifolia. Plants have the ability to maintain turgid green leaves throughout a period of anoxia and into the recovery phase. This is unusual, as leaves normally loose turgor and wither rapidly when deprived of oxygen. Tests on more southern populations from Norway, Iceland, and Scotland failed to find equivalent ability to survive oxygen deprivation. This suggests a different evolutionary history and the idea that some arctic populations may have survived the Pleistocene epoch at high latitudes in ice-free polar deserts.

Saxifraga cespitosa is considered a ‘short-distance disperser’ and a selfing polypoid (Tollefsrud et al. 1998).

North American authors as late as Porsild and Cody (1980) have recognised several races as subspecies (see above), and these races may possibly represent some reality, but the problem is that the variation has not been treated in a similar way in northwestern Europe or Russia. In Russia, subsp. monticola (Small) A.E. Porsild is recognised for Russian Far East (as S. monticola (Small) Fedde), whereas all other material is combined in S. cespitosa. Note that 'monticola' is an American name and that Porsild and Cody considered it as a Cordilleran endemic (not as a Russian or amphi-Beringian plant). The type of Small's Muscaria monticola is as follows: Canada: Alberta, Banff Natl. Park, Tunnel Mt., 23.06.1899, leg. W.C.McCalla 2288 (NY) holotype (Elven, personal communication, 2005).

This approach was followed by Zhmylev, in Elven et al. (2003). In Svalbard, Rönning (1996) recognised some characteristic yellow-flowered plants with half-closed flowers and narrow petals as a separate S. aurea (Hadač) Rönning, a name that is a homonym several times. Such plants may differ in some genetic markers (Brochmann unpublished) and have their own ecology, mainly in snowbeds. However, similar plants occur as populations elsewhere, such as, occasionally in southern and northern Norway (Elven et al. 2003).

Illustrations. • Plant habit in shade: Ellesmere Island. Plants with completely green leaves and green flowering stems, growing in rock crevices in shady conditions. Nunavut, Ellesmere Island, Tanquary Camp, scree slope at foot of Tumblerock Glacier. L.J. Gillespie 5984. CAN. • Plant habit in sun: Resolute. Plants growing in gravel in an exposed site. The stems of the plants growing in the open sun are red. Nunavut, Cornwallis Island, Resolute Bay. No voucher. • Habitat: Cape Dorset. Exposed gravelly habitat with fireweed (Chamerion latifolium). Nunavut, Baffin Island, Cape Dorset. 2 August, 2005. Aiken 05–087. CAN 586958. Scale bar in cm. • Close-up of plants: Baffin Island, Cape Dorset. Plants with flowering stems more than 10 cm high, growing in dense Low Arctic tundra with Salix arctica, Bistorta and Astragalus alpinus. Nunavut, Baffin Island, Cape Dorset. 4 August, 2005. Aiken 05–087. CAN. • Close-up of leaves. Leaves that are deeply divided into 5 lobes and coverd with white stalked glands. Centre, bulbils capable of vegetative proliferation. Nunavut, Baffin Island, Ogac Lake. July, 2004. No voucher. • Close-up of flowers. Close-up of flowers. Five green sepals with glandular hairs on the margins, 5 petals narrow at the base, 10 anthers most of which are merely filaments at this stage, and two carpels topped with whitish green stigmas. Nunavut, Ellesmere Island, Tanquary Camp, scree slope at foot of Tumblerock Glacier. L.J. Gillespie 5984. CAN. • Plant starting to fruit. Flowers beginning to set fruit. Note the presence of leaves on the flowering stem, basal leaves that have three deep lobes at the top, and densely tufted base of the plant that is the source of the name 'cespitose' saxifrage. Nunavut, Cornwallis Island, Resolute Bay. Photograph by Gary Steel. • Close-up of plant in fruit. Cespitose plants with long flowering stems topped by developing capsules. Nunavut, Baffin Island, Iqaluit. Aiken and Annie Archambault 2005. No Voucher. • Close-up of capsule. Developing capsule with short hairs on the receptacle and persisting calyx, the remains of the 10 anthers, and two widely spaced and spreading styles. Aiken and Annie Archambault 2005. No Voucher. • Close-up of infected plant. Left, part of plant intact. Right, part infected by fungus. Possibly two individuals? Norway, Svalbard, Kapp Thordsen. July, 1997. Photograph by R. Elven. • 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.