Saxifraga tricuspidata Rothb.
Prickly saxifrage, three-toothed saxifrage.
Skr. Kjobenhavnske Slesk. Laerd. Vidensk. 10: 446. 1770.
Leptasea tricuspidata (Rottb.) Haw.
Plants with erect unbranched stems arising close together, or cushion-like, or with branched or unbranched matted stems (often forming large, flat cushions); 5–15(–25) cm high. Taproot present (as the primary root from a tuft of stems). Aerial stems erect, or decumbent; glabrous, or sparsely hairy (with a few gland tipped hairs near the inflorescence). Leaves distributed along the stems; alternate (often reddish in colour); simple (vegetative leaves rigid, leathery, cuneate-spathulate with 1–3 prickly, tooth-like lobes at the apex, upper leaves on the flowering stems, linear, entire); heterophyllous; evergreen, or marcescent. Petioles absent. Blades 0.5–2 cm long; 1–4(–6) mm wide; leathery; linear, or oblanceolate, or spatulate; glabrous. Leaves lobed, or not lobed. Leaf margins with non-glandular hairs. Conspicuous hydathodes present (3 per leaf; each hydathode opens on the upper side of the leaf margin, and does not secrete lime).
Flowering stems 1–8 cm long; with leaves (leaves on the flowering stems linear, entire); hairy (with sparse glandular hairs, seen at 10x). Inflorescence cymose; 0.5–2.5 cm long. Flowers per inflorescence 3–10; medium-sized, 5–15 mm in diameter or length. Calyx sepals 5; green, or purple; glabrous (and somewhat ciliate). Petals white (creamy), or yellow (when dried); with contrasting markings (yellowish orange-red or reddish-brown or deep purple dots); ovate; unlobed; 6–7 mm long. Stamens 10. Carpels partly fused; 2. Gynoecia superior. Styles 2. Stigmas per style 1. Ovules many. Fruit with calyx persisting; ovoid (with prominent styles); 4–6.5 mm long; 3–4.5 mm wide; brown, or red; styles style modified modifying and persisting. Seeds many; 0.6–0.9 mm long; brown; smooth, or ridged (seen at 40x).
Chromosome information. 2n = 26.
Distribution. North American. Arctic. Range in the Canadian Arctic Archipelago wide-spread. Common (often forming vigorous loose mats in suitable situations, and often of considerable ecological importance). Arctic Islands: Baffin, Devon, Ellesmere, Axel Heiberg, Parry Islands, Cornwallis, Banks, Victoria, Prince of Wales, Somerset, and King William.
Ecology and habitat. The flowers and the inflorescences droop before opening, but are erect during expansion. Nectar is secreted abundantly by the thick yellow base of the ovary. It is present as small drops even before the anthers open, and the secretion is continued for a very long time, even in old flowers. Protandry occurs, but anthers and stigmas are fertile throughout the greater part of the life of the flower. Self-pollination appears to take place. Fruit has been observed to ripen in West Greenland and the Canadian Arctic. The capsules are stiffly errect and gradually split open with the onset of winter, but the opening remains relatively small. When the wind reaches a certain speed the capsules vibrate and the seeds gradually shake out. Many seed are not shed until the winds have packed the snow into a surface as smooth and hard as an asphalt road. Since the seed are shed only when the wind is blowing strongly, many of them are carried great distances in a single gale Saville, 1968.
Taxon as an environmental indicator. Variations in the height and the vigour of mats of plants of this species are dependent on local environmental conditions and indicative of the harshness of the environment. The northernmost record is Ellesmere Island, Ravine Pond, 82°30'N (CAN).
Indigeneous knowledge. Used as bedding for raising husky puppies as the prickles on the leaves are believed to cause the pads on the feet to toughen up, so that, as adult dogs, they are less likely to need booties when being used to pull komatiks (personal communication, Judith Farrow, 1986).
Notes. Galloe (1910) considered this species a xerophyte based on the habitats where it grows and the internal anatomy of leaves.
This species is not known outside of North America and Greenland. Polunin (1940) stated that "the vast majority of the specimens from our area have the leaves tricuspidate, and so belong to the typical form. Some however, especially when growing in exposed habitats, have most of their leaves lacking these conspicuous lateral teeth, and a few from widely separate parts of our area have all the leaves subentire". Polunin (1938) recognized a forma subintegrifolia (Abrom.) Polunin but this was not taken up by Porsild (1957).
Polunin (1940) stated that "S. tricuspidata varies little in our area, except in luxuriance. Thus the axes may sometimes be only 5 cm high, although generally they rise to double this height and sometimes exceed 15 cm. Such luxuriant specimens growing in the most favourable situations may form extensive mats, especially in the south. The plant generally looks reddish, but in damp and shaded crevices there occur lengthened green forms, which are usually sterile". No reason for maintaining the forma recognized by Polunin (1940) has been found.
Illustrations. • Habitat. Plants with creamy yellow flowers growing in a disturbed habitat at the base of a Thule site. Nunavut, Ellesmere Island, Alexandra Fiord at the top of the fiord. L.J. Gillespie. • Habitat. Isolated plants growing on steep rocky slope. Photograph from CMN Photo-Library. • Habit. PRICKLY SAXIFRAGE, THREE-TOOTHED SAXIFRAGE. Plants growing from basal cluster of leaves, with flowering stems with simple leaves and inflorescences with several flowers. Photograph from CMN Photo-Library. • Habit. Old flowering plants with creamy white flowers, and evidence of previous growth as limited reddish growth towards the right-hand side fo the picture. Nunavut, Ellesmere Island, Alexandra Fiord, L.J. Gillespie. • Line drawing of leaves. Fig. A, base of plant showing alternate, clustered leaf arrangement. Fig. B, leaf apex with three sharp points that feel like prickles and explain the name 'prickly saxifrage. • Close-up of flowers. Flowers have whitish petals with red and yellowish orange spots, green sepals that are much shorter than the petals, in the lower left flower, stamens that alternate with the petals and tipped with anthers, the remains of the first whorl of stamens that are opposite the petals, and in the centre of the flowers, two pale green carpels. Nunavut, Baffin Island, Pond Inlet. L.J. Gillespie, 6033. CAN. • Close-up of plants in fruit. Note dehisced capsules. Nunavut, Baffin Island, Iqaluit. Susan Aiken 97–007. CAN. Scale bar in cm. • Arctic Island Distribution.
Cite this publication as: ‘C.L. McJannet, S.G. Aiken, M.J. Dallwitz, L.J. Gillespie and L.L. Consaul. 1997 onwards. Saxifragaceae of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 28th November 2000. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), Aiken, Dallwitz et al. (1999), and Aiken, Dallwitz, McJannet, Gillespie, and Consaul (1998) should also be cited (see References).
