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 oppositifolia L.

English: Purple saxifrage, purple mountain saxifrage, opposite-leafed saxifrage,

French: Saxifrage à feuilles opposées,

Inuktitut: Aupilattunnguat.

Saxifragaceae, Saxifrage family.

Published in Sp. Pl. 402. 1753.

Type: Described from Europe, selected by Webb, Bot. J. Linn. Soc. 95: 263 1987. Lectotype: LINN 575.32, upper plant.

Synonymy. Antiphylla oppositifolia (L.) Fourr., Ann. Soc. Linn. Lyon, sér. 2, 16: 386. 1868.

Saxifraga oppositifolia L. f. pulvinata Andersson and Hesselm. in Bih. till K. Sv. Vet.-Akad. Handl. 26: 24. 1900, non Saxifraga pulvinata Small 1901.

Saxifraga oppositifolia L. f. reptans Andersson and Hesselm. in Bih. till K. Sv. Vet.-Akad. Handl. 26: 24. 1900, non Saxifraga pulvinata Small 1901.

Saxifraga pulvinata Small, Bull. New York Bot. Gard. 2: 172. 1901.

Saxifraga oppositifolia L. subsp. smalliana (Engl. and Irmsch.) Hultén, Ark. Bot., ser. 2, 7, 1: 69. 1968.

Saxifraga oppositifolia L. subsp. euoppositifolia var. typica subvar. smalliana Engl. et Irmsch., in Engl., Pflanzenreich IV.117 (67): 624. 1916.

Saxifraga oppositifolia L. subsp. glandulisepala Hultén, Bot. Not. 126: 492. 1973.

Saxifraga oppositifolia L. subsp. reptans (Andersson and Hesselm.) Rönning, nom. inval., Svalbard. Fl., ed. 3, 115. 1996.

Saxifraga oppositifolia L. subsp. pulvinata (Andersson and Hesselm.) Rönning (1996), nom. inval., Svalbard. Fl., ed. 3, 115. 1996.

Saxifraga oppositifolia L. subsp. reptans (Andersson and Hesselm.) Rönning, nom. inval., Svalbard. Fl., ed. 3, 115. 1996.

Saxifraga oppositifolia L. subsp. pulvinata (Andersson and Hesselm.) Rönning, nom. inval., Svalbard. Fl., ed. 3, 115. 1996.

Vegetative morphology. Plants 2–5 cm high (rarely to 10 cm high where plants are etiolated); perennial herbs (with a tendency to become a sub-shrub as the branches become woody); caespitose (in the tightly tufted cushion-form), or not caespitose (trailing form). Taproot present (rarely collected). Ground level or underground stems absent (cushion-form), or horizontal (trailing plants); rhizomatous. Horizontal stems at ground level, branching extensively to shape plant habit as mats, or cushions. Caudex absent. Aerial stems erect (branched and sometimes very highly compacted), or prostrate (with trailing stems). Leaves present; distributed along the stems (often imbricate, and densely overlapping); opposite (4-ranked); persistent and marcescent (leaves turn red in the fall, but only some die off over winter, others become green again after snow melt). Petioles absent. Leaf blades simple. Leaf blade bases truncate, or attenuate. Leaves not grass-like. Blades 2.5–4 mm long, 2–3 mm wide, obovate, flat, with inconspicuous veins. Blade adaxial surface glabrous. Blade abaxial surface glabrous. Blade margins entire, with non-glandular hairs (stiff bristle-like trichomes). Hydathodes present and conspicuous (usually 1, rarely more, seen as pores on the thickened, often flat, apex of the leaf; often with white calcium carbonate deposits). Blade apices rounded (or truncate).

Reproductive morphology. Flowering stems two or more per plant; with leaves (distinct from the leaves on the flowering stems often more widely spaced, narrower, attenuate at base, and without conspicuous truncate apices or hydathodes). Flowers solitary. Flowers medium-sized. Sepals conventional; 5; free; 1.5–2.5 mm long; 3.5–4.5 mm wide; green, or purple. Calyx glabrous, or hairy. Calyx hairs pilose (if applicable); glandular, or non-glandular (if applicable). Calyx margins ciliate (with large, stiff cilia). Petals conventional; free; 5 (rarely 4 or 6); purple, or pink, or white (rarely); obovate (with narrow bases); unlobed; 6–9 mm long; 3–4 mm wide. Stamens 10. Nectaries present. Receptacle 1.5–2.5 mm high. Ovary partly inferior; carpels 2 (rarely 4–5); partly fused. Ovaries glabrous. Placentation axile. Ovules per ovary 50–100 (approx.). Fruit with calyx persisting (corolla persistent); dry; a capsule; spherical (lower half, with divergent free carpels above); brown, or red (purplish); 5–7.5 mm long; 4–5 mm wide; dehiscent; splitting to the base into separate segments. Seeds 50–100 (approx.); 0.7–1.1 mm long; brown; surfaces smooth, verrucose (at one end).

Chromosome information. 2n = 26, 39, 48, 52, and 56.

(2n) (2x) = 26. Skovsted (1934); Böcher (1941, Greenland?); Sørensen and Westergaard, in Löve and Löve (1948, Greenland); Löve and Löve (1951, 1956, Iceland; 1982a, Arctic Canada); Holmen (1952, Greenland); Larsen (1954); Jørgensen et al. (1958, Greenland); Sokolovskaya (1958); Sokolovskaya and Strelkova (1960); Packer (1964, northwestern Canada); Mosquin and Hayley (1966, northern Canada); Knaben and Engelskjøn (1967, Norway); Taylor and Mulligan (1968, western Canada);

(2n) (3x) = 39. Jørgensen et al. (1958, northeastern Greenland, as S. oppositifolia s.s.);

(2n) = about 48. Zhukova and Petrovsky (1972);

(2n) (4x) = 52. Flovik (1940, Svalbard); Löve and Löve (1951, Iceland, not included by Löve and Löve 1975); Hedberg (1967, northern Canada); Zhukova (1967a, 1982, northeastern Asia); Johnson and Packer (1968, northwestern Alaska); Petrovsky and Zhukova (1981, Wrangel Island); Zhukova and Petrovsky (1987a, northeastern Asia); Chapman (1995, Svalbard);

(2n) = 56. Zhukova (1980, western Chukotka).

Elven (personal communication, 2005) noted that there are two ploidy levels represented by 2n = 26 and 52, functionally di- and tetraploid, with a few deviating counts. Diploid numbers occur throughout, whereas tetraploid numbers are documented from Beringia, northern Canada, and Svalbard. He sorted the counts geographically as below.

Mainland Europe (subsp. oppositifolia): 2n (2x)= 26. Skovsted (1934, southern Norway); Knaben and Engelskjøn (1967 Norway two counts). Several more southern counts.

Northern European Russia and Siberia (subsp. oppositifolia): 2n (2x) = 26. Sokolovskaya (1958, northern Russia); Sokolovskaya and Strelkova (1960, northern Russia).

Beringian northeastern Asia (subsp. smalliana): 2n = about 48. Zhukova and Petrovsky (1972, Wrangel Island).

2n (4x) = 52. Zhukova (1967a, Wrangel Island, 2n = about 52, 1982, northeastern Asoa); Petrovsky and Zhukova (1981, Wrangel Island); Zhukova and Petrovsky (1987a, mainland Chukota and Wrangel Island eight counts).

2n = 56. Zhukova (1980, western Chukotka).

Beringian northwestern North America (subsp. smalliana):

2n (4x) = 52. Johnson and Packer (1968, northwestern Alaska).

Cordilleran western North America (race uncertain):

2n (2x) = 26. Packer (1964, western Canada, Alberta); Taylor and Mulligan (1968, western Canada, BC).

Non-Beringian northern Canada and Greenland (both subspecies):

2n (2x) = 26. Böcher (1941 Greenland); Sørensen and Westergaard, in Löve and Löve (1948, Greenland); Holmen (1952, Greenland); Larsen (1954, Greenland); Jørgensen et al. (1958, Greenland); Mosquin and Hayley (1966, northern Canada, Melville Island); Löve and Löve (1982a, northern Canada, Churchill).

2n (3x) = 39. Jørgensen et al. (1958, northeastern Greenland as S. oppositifolia s.s.).

2n (4x) = 52. Hedberg (1967, northern Canada, Southampton Island).

Svalbard (assumed as mainly subsp. oppositifolia):

2n (4x) = 52. Flovik (1940); Chapman (1995).

Iceland (subsp. oppositifolia), di- and tetraploid counts by the Löve and Löve (1951, 1956b) and partly not confirmed by Löve and Löve (1975).

Ploidy levels recorded 2x, 3x, and 4x.

Indigenous knowledge. An Inuit name for this plant is aupilattunnguat. Etymologically, it means "resembling something red". The flowers, which have a pleasant fresh taste, are often eaten in large quantities when they appear early in the growing season. Too many of the flowers eaten at once can induce diarrhoea. The flowers are good eaten with blubber (Ootoova et al. 2001) or a mixture of seal fat and seal blood (Eva Aariak, personal communication, 2006). The leaves can be used as tea. This is best done with dried leaves (Eva Aariak, personal communication, 2006).

The flowers "can be eaten along with the leaves but you tend to get tired of them even before you get full... If one is only going out for a walk, one would eat edible plants, but when you start for home, you would feel that you had too much of plant, even your chest does not feel good" (Z. Innuksuk, personal communication, reported in Mallory and Aiken, 2004, p. 111).

Taxon as an environmental indicator. This species is usually indicative of harsh environments where there is little competition from other species. Saxifraga oppositifolia is one of the four species of plants known from the northernmost botanical locality on earth, that is, Lockwood Island, 83°24'N, on the north coast of Greenland. It has been collected in Canada on Ward Hunt Island, 83°05'N.

Ecology and habitat. Substrates: hummocks (on the sides), around the margins of ponds, along streams, river terraces, lakeshores, tundra (raised centres of frost boils, solifluction slopes), slopes (of herbmats), seashores (just above high tide on beach ridges); imperfectly drained moist areas, dry, moderately well-drained areas; gravel (fell field, shale, rocky mountain slopes, drumlin surfaces), till, moss; with low organic content (granitic-schist), with high organic content, peat; acidic, or calcareous. The species characterises extensive Saxifraga oppositifolia barrens (illustrated in the image library). Plants occasionally grow in moss and in standing water (two observations made at different locations on Ellesmere Island in 1994).

Saxifraga oppositifolia is almost always the earliest "flower" to appear in spring, although sometimes some of the willows will be earlier by a day (Polunin 1940). The flowers overwinter in a well-developed condition. In December, in Greenland, petals and stamens were already coloured (Warming 1909). In West Greenland, they have been observed to flower as early as late March. Plants from Svalbard to Novaya Zemlya are reported to have flowers with a strong scent. Nectar is often secreted abundantly from the base of the ovary. Flowers are initially protogynous, and the stigmas mature before the flowers are fully expanded. At first the styles are longer than the stamens, but gradually the anthers become as long as the styles, and gather so closely around them that self-pollination takes place. Functionally staminate flowers occur, the gynoecium very small, with stamens of normal length. Such flowers do not set fruit. Pistillate flowers have been observed. In these, the stamens were almost rudimentary or sterile (Warming 1909).

Wagner and Tengg (1993) studied the embryogenesis and seed development of S. oppositifolia plants growing in northern European mountains. They found that immediately before the flowers open, the ovules are in the post-meiotic state and not ready for fertilisation until the flowers are fully open. After fertilisation, there is a delay of 2–3 weeks before the development of helobial endosperm begins. The differentiation and ripening of the seeds takes a total of 11 weeks.

North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador, Newfoundland. Range in the Canadian Arctic Archipelago widespread. Common. Arctic. Arctic islands: Baffin (Bylot, Mill, Prince Charles, Resolution), Devon, Ellesmere, Axel Heiberg, Amund Ringnes, Ellef Ringnes, Parry islands (Bathurst, Borden, Eglington, Melvile, Prince Patrick), Cornwallis, Banks, Victoria, Prince of Wales, Somerset, King William, Coats (Loughead).

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 circumpolar arctic-alpine species shows considerable variability of habit, cilia length and hydathode number on the leaves, shape and pubescence of sepals, size and colour of petals. However, the geographical pattern of this morphological polymorphism is not clear. In this connection the majority of botanists accept a broad interpretation of S. oppositifolia (Zhmylev, in Elven et al. 2003).

The variation in S. oppositifolia was the basis of a study by Teeri (1972) at Truelove Inlet, Devon Island. He concluded that distinct forms had been named as taxa, which were merely expressions of a single species that shows remarkable vegetatively phenotypic plasticity with little reliable genotypic basis on which to separate infraspecific taxa.

Brysting et al. (1996) studied the purple saxifrage on Svalbard to determine whether there were two taxa or one. They concluded the conspicuous variation probably results from local, in situ ecoclinal differentiation, which is without taxonomic significance but is important in the context of arctic conservation biology and the potential impact of global warming on Arctic vegetation.

Boris Yurtsev has suggested that there are two taxa within S. oppositifolia in Canada, one with glabrous sepals, the other with glandular hairs on the sepals (personal communication, 1997). In a survey of specimens at CAN plants with glandular sepals there were plants with specimens with densely matted hairs on the sepals, and others with sparse or few hairs. The type specimen of the name "smalliana" has almost no hairs on the sepals.

Polunin (1940) considered this to be one of the common species in the Arctic Archipelago and possibly one of the most numerous of all arctic species. It dominates large tracts of country in the Far North, if the ecological term "dominates" can be used when the total vegetation is extremely sparse and largely limited to occasional tufts of this one species. He considered it possibly the hardiest of all phanerogams, at least in cold-rigour, occurring on the most exposed ridges and hill tops, often where no other vascular plants can grow. This may be because of the unique structure of the leaves. Elven (personal communication, 2005) noted that this is the northernmost flowering plant in the world, occurring as it does on the off-shore islands north of Greenland. Polunin (1940, p. 268) remarked that "S. oppositifolia ... before and after flowering is among the most squalid-looking of plants, forming untidy brownish mats or tussocks in barren and often dusty situations. When it blooms it must be reckoned among the world's greatest beauties, especially as it stands out in its usually bleak and desolate surroundings. Unfortunately, few ever see it at its best, which is surely in the Far North, for it is so quickly over that the vast majority of the ever-increasing band of summer visitors to arctic parts come too late."

The internal structure of the leaves led Galloe (1910) to consider this species a xerophyte. The upper epidermal cells have fairly straight lateral walls with numerous pits. Only the part of the leaf that is covered with neighbouring leaves bears stomata, while the light-exposed surface is almost without them. This was regarded as protection against excessive transpiration by Lazniewski (1896). Galloe (1910) considered the distribution of the stomata represented a primitive form of bud-protection in developing leaves in a species where bud scales are absent.

Gabrielsen et al. (1997) analysed 18 populations of this species from Norway, Svalbard, and Novaya Zemlya, using RAPDs DNA technology, and found more variation in the populations from the High Arctic than further south. Their results suggested that there is more inbreeding towards the north, probably because of lower pollinator activity.

Gugerli et al. (1999) investigated the genetic variation of S. oppositifolia from 10 populations of the Alps in southern Switzerland using RAPDs. They found the genetic variation was mainly within populations (95%), whereas less than 5% was found among populations. They assumed the high outcrossing rate, rare clonal reproductions, and some long-distance dispersal even among topographically separated populations are the crucial determinants for the pattern of genetic variation found in the investigated areas.

Abbot et al. (2000) examined the chloroplast DNA (cpDNA) restriction site variation among 548 plants sampled from 90 different populations from around the circumpolar and circumboreal area and found 14 cpDNA haplotypes. From their phylogenetic analysis of the cpDNA variation, they suggested that this species first occurred in the Arctic in western Beringia before it migrated east and west to achieve a circumpolar distribution. They suggested that the geographical distribution of cpDNA variation in the species supports the hypothesis that during Pleistocene glaciations, some plant refugia were located in the Arctic as well as at more southern latitudes.

Aiken et al. (2005) examined growth forms and the presence or absence of hairs on the surfaces of the sepals of plants of Saxifraga oppositifolia L., on type specimens and for more than 400 herbarium specimens collected from all over North America and Europe. No morphological differences are associated with three different chromosome numbers known for S oppositifolia plants from the area of the North American type specimens, and DNA analyses done mainly on European specimens but also including a potential candidate for the name ‘smalliana’ gave inconclusive results. Thus, chromosome and DNA data join these morphological data on growth forms and the occurrence of sepal hairs, to discourage recognising subspecies among plants occurring in North America. Aiken et al. (2005) reported that the type specimen of S. oppositifolia subsp. smalliana (S. pulvinata) from the Yukon has compact plants and flowers that have sepal surfaces with a few sparse hairs.

Illustrations. • Habitat. Saxifraga barren. Purple colour is from the flowering plants of the purple saxifrage. Nunavut, Ellesmere Island, Alexandra Fiord, at the top of a mountain. L.J. Gillespie. • Habitat. Loamy upper beach characterised (and coloured) by Saxifraga oppositifolia. Norway, Svalbard, Kapp Waern. July, 1997. Photograph by R. Elven. • Habitat. Loamy upper beach with hummocks and Saxifraga oppositifolia on (nearly) all of them. Norway, Svalbard, Kapp Waern. July, 1997. Photograph by R. Elven. • Habitat: Dorset. Intermediately compact plants growing against rock beside stream. Nunavut, Baffin Island, Cape Dorset. 3 August, 2005. Aiken. No voucher. • Close-up of trailing plants: Dorset. Trailing plants. Plants less than 2 m from the previous image, growing over rocks on the other side of the runoff. Nunavut, Baffin Island, Cape Dorset. 3 August, 2005. Aiken. No voucher. • Plant habit. Loosely clustered plant with opposite leaves that have long trichomes on the margins. Note flower born singly. Nunavut, Ellesmere Island, Alexandra Fiord. L.J. Gillespie. • Plant habit. Compact cushion-like plants in full flower growing in saxifraga barren. Nunavut, Ellesmere Island, Alexandra Fiord. L.J. Gillespie. • Side view of flower. Sepals with most of the surface glabrous (A), stiff cilia on the margin (B), similar cilia on the leaves (C). Note hydathode without calcite (D) and with calcite (D). 2004. Aiken. • Close-up of flower. Flower with 5 purple petals, 10 anthers, and two carpels topped with receptive pale pink stigmas. Baffin Island, Ogac Lake. July, 2004. Photographed by LeBlanc. • Line drawing of plant habit. A, a flowering stem that is leafy to just below the flower. B, opposite leaf arrangement. C, elongated fruiting stem. D, trailing growth form and E, compact growth form that has been distinguished by some authors using the name 'smalliana'. Warming 1909. p. 205. • Leaves with hydathodes. Small, opposite, fleshy leaves have large trichomes on the margins and hydathodes (white arrow) on the triangular leaf tips. Many hydathodes have white calcite deposits. Nunavut, Cornwallis Island, Resolute Bay. Photo by Gary Steel. • Plant in fruit. Flowers with carpels in fruit. Nunavut, Ellesmere Island, Vendom Fiord, plants growing in sand of a flood plain. Photograph by Carmen Lee. • Plant in fruit. Note long peduncles and hairs on the sepals. Dehisced anthers have persisted around the dark red diverging carpels. Nunavut, Cornwallis Island, Resolute Bay. CAN. August, 1998. Photograph by Mollie MacCormac. • 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.