Flora of the Canadian Arctic Archipelago
| Flora of the Canadian Arctic Archipelago | |
English: Alpine saxifrage, clustered alpine saxifrage, snow saxifrage,
French: Saxifrage des neiges.
Saxifragaceae, Saxifrage family.
Published in N. Amer. Fl. 22: 136. 1905.
Type: Selected by Jonsell and Jarvis, Nord. J. Bot. 22: 72. 2002. Lectotype: LINN 575.19, the specimen furthest to the right. These authors reject the lectotype proposed by Webb, Bot. J. Linn. Soc. 95: 262–263 (1987), i.e., LINN 575.18, left-hand specimen, as post-1753 material.
Synonymy. Saxifraga nivalis L., Sp. Pl. 401. 1753.
Micranthes kumlienii Small, N. Amer. Fl. 22: 144. 1905.
Saxifraga nivalis L. var. rufopilosa Hultén, Ark. Bot., ser. 2, 7, 1: 69. 1968.
Saxifraga rufopilosa (Hultén) A.E. Porsild, Nat. Can., Bot. 4: 41. 1975.
Vegetative morphology. Plants (3–)4–10 cm high (to 17 cm high, CAN 125631); perennial herbs; caespitose. Roots black. Ground level or underground stems absent. Caudex absent. Aerial stems erect. Leaves basal in a rosette; patent; alternate; persistent. Petioles absent (attenuated leaf bases (0.2-)0.5–2.5 wide may appear petiole-like). Leaf blades simple. Leaf blade bases obtuse, or attenuate (broadly). Blades 6–36 mm long (mean 14 mm), 4–21 mm wide (mean 10 mm), ovate or obovate or spatulate, flat, appearing single-veined or with inconspicuous veins. Blade adaxial surface glabrous. Blade abaxial surface glabrous or hairy, hairs pilose or villous (if applicable), hairs sparse or moderately dense, hairs a mixture of white and rust-coloured. Blades lobed or not lobed. Blade margins serrate or crenate, with glandular hairs and with non-glandular hairs (that are long, tangled and brown and seen), with 4–7 teeth on each side of the blade, with teeth toward the apex; apices obtuse, or rounded, or acute (rarely).
Reproductive morphology. Flowering stems solitary; without leaves (usually), or with leaves (occasionally, bract-leaves close to the inflorescence). Flowering stems hairy. Flowering stems pilose, or villous. Flowering stem hairs simple; white or translucent, or transparent with deep purple cross-walls (occasionally); glandular hairs present, or absent (some longer crisped white hairs). Inflorescences spicate, or head-like (flowers in 1–2 dense clusters with bracts subtending the flowers); 1–2(–4) cm long. Pedicels present; with glandular hairs. Flowers per inflorescence (1–)3–10(–15); small, or medium-sized. Sepals conventional; 5; free; (1–)1.5–2.5 mm long; 2–3 mm wide; green, or purple. Calyx glabrous. Petals conventional; free; longer than the calyx, or same length as the calyx; 5; white (rarely greenish yellow, or reddish to light pink); without contrasting markings (although tips of the petals are sometimes reddish); ovate, or elliptic (sometimes clawed); unlobed; (1–)1.5–2.5(–3) mm long (mean 1.9 mm); 0.6–1.5(–1.8) mm wide (mean 1.1 mm). Stamens 10. Nectaries present. Receptacle 1.8–2.4 mm high. Ovary partly inferior; carpels 2; partly fused. Ovaries glabrous. Placentation axile. Ovules per ovary 50–100 (approx.). Fruit with calyx persisting; dry; a capsule; spherical (plump lower half, free portion of the carpels straight or slightly divergent); brown, or purple; 3–4 mm long; (3–)4–5(–5.5) mm wide; glabrous; dehiscent; splitting to the base into separate segments. Seeds 50–100 (approx.); 0.5–1 mm long; brown (yellowish); surfaces verrucose.
Chromosome information. 2n = 56–62, or 70.
(2n)(6x = 56-60-62). Flovik (1940, Svalbard); Sørensen and Westergaard, in Löve and Löve (1948, Greenland); Böcher and Larsen (1950, Greenland); Löve and Löve (1951, 1956, Iceland); Holmen (1952, Greenland); Jørgensen et al. (1958, Greenland); Sokolovskaya (1958, 1963, 1965, northeastern Asia; 1970); Sokolovskaya and Strelkova (1960, 2n = about 60); Mosquin and Hayley (1966, northern Canada); Hedberg (1967, northern Canada, 2n = about 56); Knaben and Engelskjøn (1967, Norway); Johnson and Packer (1968, northwestern Alaska); Zhukova (1968, 1982, northeastern Asia); Packer and McPherson (1974, northern Alaska); Krogulevich (1976a, northern Siberia); Zhukova and Petrovsky (1976, western Chukotka; 1987b, northeastern Asia); Engelskjøn (1979, Norway and Bear Island, 2n = 60, 60–62); Yurtsev and Zhukova (1982, northern Siberia); Dalgaard (1989, western Greenland); Devyatov et al. (1997, northeastern Asia). A few more southern counts.
(2n) (7x) = about 70. Devyatov et al. (1997, northwestern Siberia).
Ploidy levels recorded 6x.
Taxon as an environmental indicator. This species varies according to the quality of the habitat, from the smallest dwarf-forms to robust "gigantic specimens" (Porsild 1957). The size of the plant is a reflection of growing conditions in the environment. The northernmost record is Low Point, 83°06'N, on the north coast of Greenland. It has been collected in Canada on Ward Hunt Island, 83°05'N (Canada).
Ecology and habitat. Substrates: hummocks, tundra, slopes, cliffs, barrens; dry, moderately well-drained areas (usually on sloping ground. In Greenland, it has been found to be three times more likely on the sunny side than the damp shady side of a slope (Galloe 1910)); rocks, gravel, sand, silt, clay, till, moss; acidic, or nitrophilous (growing most luxuriantly on manured soils around bird-cliffs, especially in seepage crevices and Inuit middens. It can also grow in very barren areas), or calcareous (weakly calcareous colluvial sand and silt). The flowers pass the winter well developed and are among the first to open in the spring. Nectar is secreted by the glistening greenish base of the styles. After rain, a large collection of water, evidently containing nectar, can be seen at the bottom of the flower; scent is absent (Warming 1909).
Protandry is the rule for the flowers of this species in Greenland, but both sexes are mature during the greater part of the flowering period. Self-pollination appears to be very common and is at any rate easily possible if cross-pollination does not occur. Fruit usually ripens in West Greenland and on Ellesmere Island.
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 (more common in the northern part of the area, and relatively common throughout, but never noted as really abundant or important). Arctic. Arctic islands: Baffin, Devon, Ellesmere, Axel Heiberg, Amund Ringnes, Ellef Ringnes, Parry islands, Cornwallis, Banks, Victoria, Prince of Wales, King William, and Southampton.
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 in high-arctic regions may be confused with M. tenuis, owing to its small size. It differs from that taxon in having more densely hairy flowering stems with much longer hairs, capitate flowering heads with flowers on very short pedicels, and a sharp separation between the leaf blades and the petioles, and in being hexaploid versus diploid, as in M. tenuis.
Healy and Gillespie (2005) investigated the systematics of Canadian Arctic Island members of this complex from 157 specimens, using 23 morphological characters. They noted that most European studies suggest that the nivalis complex includes two distinct species: M.nivalis s.s. and M. tenuis, but , inconsistencies in chromosomal counts, variability in morphological keys and descriptions, and specimens with intermediate morphology have led to different taxonomic interpretations of the complex in North America. Principal component analysis of the morphological data revealed two adjacent clusters, corresponding to the two taxa and consistent with a close morphological similarity and possible presence of hybrids. A preliminary restriction site analysis of five non-coding regions of the chloroplast genome, indicated a length difference in the trnT-trnF region between M. nivalis and M. tenuis, but no difference in restriction sites for any of the regions. The authors concluded that their results confirm that in the Canadian Arctic, the S. nivalis complex consists of two closely related, largely sympatric species, with morphological variability and possible hybrids.
Elven (personal communication, 2005) noted that the same pattern appears from studies by the Brochmann group at Oslo. Tetraploid (2n = 40) hybrids have not yet been found in the Canadian Arctic. There may be possible single hybrid individuals in mixed populations, but there is as of yet no support for a propagating tetraploid entity here. Tetraploid individuals and a putative tetraploid entiy in the M. nivalis complex have been found in North America outside of the arctic (Krause and Beamish 1973; Gervais et al. 1995) and in the Russian Arctic (Devyatov et al. 1997).
Anatomically, this species was considered to be a mesophyte (Galloe 1910) because the leaves have prominent stomata upon both surfaces, thin-walled epidermal cells, and a spongy parenchyma.
Polunin (1940) considered the typical form to be the most frequent in the Canadian Arctic Archipelago. He indicated that it is rather coarse, growing generally 8–20 cm high, and occurring almost everywhere. He noted that Micranthes kumlienii Small was described as a new species from within the area. Polunin (1940) was unable to separate it from the species described here, either on the basis of the original diagnosis or on the type material he had seen, and he considered that it clearly belonged to M. nivalis. The chief distinction on which Micranthes kumlienii was recognised was in having unusually fine dentation of the leaves, but this is a variable character.
Illustrations. • Habitat. Plant in fruit growing among lichens and moss on rocky slope. Note basal rosette of simple leaves with shallowly divided margins and flowering stem without leaves. Nunavut, Baffin Island, Pond Inlet. L.J. Gillespie 6056. CAN. • Habitat: Baffin Island, Ogac Lake. Plants near the markers, growing among rocks on a talus slope. Nunavut, Baffin Island, Ogac Lake. 12 July, 2004. Aiken and LeBlanc 04–077a. CAN. • Habit. Note basal rosette of leaves that are reddish underneath, the leafless scape covered in glandular hairs, and several clustered flowers borne in the axils of purple-red bracts. The flowers have green sepals, white petals, and reddish carpels. Nunavut, Baffin Island, Pond Inlet. L.J. Gillespie 6056. CAN. • Habit: Baffin Island. Plant more than 10 cm high, with a branching flowering stem. Nunavut, Baffin Island, Iqaluit. Aiken and A. Archambault 05–069. CAN 586941. • Scape hairs. The long shaggy hairs, often as long as the scape is thick, separate S. nivalis from S. tenuis that has short and predominantly glandular hairs. Norway, Svalbard, Kapp Thordsen. August, 1997. Photograph by R. Elven. • Close-up of flower. Flowers have 5 sepals that are green on the upper surface and reddish purple underneath, 5 white petals, 10 small yellow anthers and two large reddish purple carpels that are fused at the base and diverge at the tops. L.J. Gillespie 6056. CAN. • Side view of inflorescence. Inflorescence with several flowers in the main inflorescence and one lateral flower at a young stage of flowering. Nunavut, Baffin Island, Ogac Lake. 12 July, 2004. Aiken and LeBlanc 04–077a. CAN. • Close-up of flowering head. Head-like inflorescence. Centre, a flower beginning to open. Left, a flower showing two carpels with sessile stigmas. Aiken and LeBlanc 04–077a. CAN. • Close-up of plant. Small plant 7 cm high with a compact inflorescence. See discussion on differences from M. tenuis in General Notes. Nunavut, Baffin Island, Ogac Lake. CAN 586517. • Close-up of hairs on scape. Close-up on hairs on the scape of the CAN 586512 specimen. Reidar Elven considered the hairs characteristic of this taxon even though some appear to be glandular. Nunavut, Baffin Island, Ogac Lake. Aiken and LeBlanc 04–048. CAN 586512. • Close-up of plant. Leaf blades with no hairs on the undersurface. Nunavut, Baffin Island, Ogac Lake. Aiken and LeBlanc, 04–079. CAN 586548. Image identified as M. nivalis by Reidar Elven, Oct. 2005. • Close-up of hairs on scape. Note the short hairs on scape approaching those characteristic of Micranthes tenuis. Nunavut, Baffin Island, Ogac Lake. Aiken and LeBlanc 04–079. CAN 586548. Plant image identified as M. nivalis by Reidar Elven, Oct. 2005. • Plant in fruit. Close-up of fruiting inflorescence showing wilted remains of whitish petals and pairs of large diverging carpels that are fused only at the base. Nunavut, Baffin Island, Pond Inlet. L.J. Gillespie 6056. CAN. • Surface view of fruit. Fruit surrounded by 5 persisting sepals and the red filament remains of 10 stamens. Centre, two fused carpels with widely spaced short styles. Left, recently receptive stigma with pollen on the surface. Right, withering style with dried up stigma. Nunavut, Baffin Island, Iqaluit. August, 2005. Photograph by Kathy Thornhill. No voucher. • 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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