The Flora of Svalbard

Very restricted vegetative growth, forming small colonies. Efficient reproduction only by seeds. Flowering is regular, but late in the season. Flowers adapted to insect pollination. Assumedly with regular seed set, but the seeds seem mainly unripe and their germination percentage is <5% (Alsos et al. in prep.; Müller et al. 2011). Capsules have apical opening which ensures that the seeds only are dispersed out at a minimum wind speed. Seed dispersal is often after the first snow fall, which increases the dispersal distance as the seeds are blown across a smooth surface (Savile 1972). Seeds are also dispersal by animals, e.g. geese that selectively feed on seed capsules (Prop et al. 1984). Secondary dispersal by water or wind.

The three yellow-flowered Saxifragas of Svalbard are quite different. Saxifraga platysepala is distinguished from the two others by its long, above-ground runners (stolons) ending in small rosettes (the "Spider Plant") and being glandular pubescent. Saxifraga hirculus and S. aizoides are separated by entire vs. dentate–ciliate leaves, and by a large and usually single flower per stem vs. small and mostly several flowers per stem.

Not thermophilous, but not present in the harshest environments in Svalbard. Most common in moss tundra and other moist tundras with dense vegetation. Also recorded from soil banks, and rarely in shallow mires. On fine textured to mixed soils with impeded to moderate drainage, and weakly acidic to basic soil reaction. Probably requiring good protection from snow during winter, but not adapted to short growing seasons as in snowbeds. Little grazed by reindeer and geese.

Saxifraga hirculus is very polymorphic and several geographical races have been proposed. The main plant in temperate and boreal regions, in both Eurasia and North America, is the tetraploid (2n = 32) ssp. hirculus, tall-grown and with extensive stolons, forming very loose carpets in wet mires. The plants occurring in Svalbard and Iceland have been assigned to ssp. alpina (Engl.) Á.Löve (Löve 1970), but this is an evident misapplication by Löve of Engler's name based on a plant from the Himalayas (see Webb & Gornall 1989). In a revision by Hedberg (1992), the plants in the European and Siberian Arctic were assigned to a tetraploid (2n = 32) ssp. compacta, described on a type from Svalbard, whereas those in the Greenland and American Arctic mainly were assigned to the diploid (2n = 16) ssp. propinqua, based on a plant from Melville Island in the Canadian Arctic. Hedberg's revision is supported by differences in morphological features and in ploidy levels, but has not been generally accepted. In the only molecular study known to us (Oliver et al. 2006), geographical entities (races) were not well supported. The only population from Svalbard analysed by Oliver (2006) showed two haplotypes unique to Svalbard, but their relations to populations from other geographical regions are not obvious.

Alsos, I.G., Müller, E. & Eidesen, P.B. In prep. Germinability of 87 arctic species stored in Svalbard Global Seed Vault.

Hedberg, O. 1992. Taxonomic differentiation in Saxifraga hirculus L. (Saxifragaceae) – a circumpolar arctic–boreal species of Central Asiatic origin. – Botanical Journal of the Linnaean Society 109: 377–393.

Löve, Á. 1970. Emendations in the Icelandic flora. – Taxon 19: 298–302.

Müller, E., Cooper, E.J. & Alsos, I.G. 2011. Germinability of arctic plants is high in perceived optimal conditions but low in the field. – Botany 89: 337-348.

Oliver, C., Hollingsworth, P.M. & Gornall, R.J. 2006. Chloroplast DNA phylogeography of the arctic-montane species Saxifraga hirculus (Saxifragaceae). – Heredity 96: 222–231.

Webb, D.A. & Gornall, R.J. 1989. A manual of Saxifrages and their cultivation. – Timber Press, Portland, Oregon.