Life span

Perennial, but not very long-lived.

Growth form

Solitary herb with basal caudex, slightly covered by leaf remains, with a single rosette or branching into several clustered rosettes and forming small, loose tussocks. Each rosette potentially with one scape without leaves. Scapes ascending or erect, strongly elongating during and after flowering to (5)10–20(25) cm, sparsely pubescent with small cruciform, irregularly branched, and slender simple hairs.

Leaf

Leaf rosettes up to 5 cm. Leaves alternate, to 30 × 8 mm, oblanceolate or obovate, acute, entire or rarely with 1–2 teeth, mid vein not prominent, green. Upper leaf surface glabrous or sparsely pubescent with small hairs, cruciform or irregularly branched, more rarely forked or simple; lower leaf surface sparsely to moderately pubescent with the same hair types; margins with simple hairs up to 1 mm and much smaller branched hairs.

Inflorescence

Inflorescence a raceme mostly with 3–6 flowers but occasionally up to 20, very short in flowering stage but up to 4–5 cm in fruiting stage. Pedicels 3–6 mm, stout, attached at an angle with scape of 40–60° but regularly curved upwards, either with predominance of simple hairs or with a mixture of simple, cruciform and irregularly few-branched hairs.

Flower

Flower radially symmetric with 4 free sepals and petals. Sepals up to 3.5 × 1.7 mm (i.e., ca. twice as long as broad), narrowly ovate, elliptic or obovate, dark greyish green and often with some purple colour, with very narrow white margins. Petals up to 7 × 3 mm, not contiguous or overlapping, erectopatent (making the flower half-open), narrowly obovate or spathulate, notched, bright yellow (rarely pale yellow).

Fruit

Fruit a silicule up to 7 × 4 mm, erect to erectopatent, elliptic to narrowly ovate, glabrous, rarely sparsely to more densely pubescent with small simple hairs on valves and margins, dark greyish green. Style short, up to 0.3 mm. Seeds 7–10 in each room, medium brown, up to 1.3 × 1.0 mm.

Reproduction

Sexual reproduction by seeds; no vegetative reproduction. Flowering and seed-set is regular and abundant in most years; mature seeds are regularly observed. Germination of 72 % after scarifying seeds with sand paper (Alsos et al. 2013).

There is no special adaptation to seed dispersal.

Comparison

The five yellow-flowered Draba species found in Svalbard – D. alpina, D. corymbosa, D. micropetala, D. oxycarpa, and D. pauciflora – are very often confused. Draba alpina is most similar to D. oxycarpa. The most reliable diagnostic characters seem to be the following: In D. alpina the petals are comparatively narrow and erectopatent, the sepals are narrow, ca. 2 times as long as broad and purplish tinged, the fruit stand is elongated, the fruits glabrous or sparsely hairy also on valves, and the seeds medium brown and slightly smaller (1.3 × 1.0 mm); in D. oxycarpa the petals are broader and patent, the sepals are broader, 1–1.5 times as long as broad and not purplish tinged, the fruit stand subcorymbose, the fruits hairy only marginally on the suture between the valves, and the seeds blackish and slightly larger (1.4 × 1.1 mm).

For differences from D. corymbosa, see that species.

Habitat

Most common in snowbeds and other moist site types like moist tundra, gravelly river banks, and bird cliff meadows. Also at disturbed sites like roadsides and soil and gravel deposits. On fine textured soil among boulders on both calcareous and siliceous substrates. Adapted to long duration of snow cover and shortened growth season but also present at more exposed sites with less snow as long as there is abundant moisture in the ground. Probably not much grazed by reindeer or geese.

Distribution

Present in all zones and sections but less common in the polar desert zone and the clearly continental section than in the others. Frequent to common on most of the major islands in the Spitsbergen group (Spitsbergen, Prins Karls Forland, Nordaustlandet, Edgeøya) and also on Bjørnøya.

The general range of Draba alpina s. str. is amphi-Atlantic, from NE Canada across Greenland and the North Atlantic to Fennoscandia and N European Russia (see also Comments).

Comments

The name Draba alpina has in many regions and until quite recently been applied collectively for all northern yellow-flowered species of Draba. Genetic investigations have shown that the five yellow-flowered species of Draba recognized from Svalbard are distinct and deserve rank as independent species (Brochmann et al. 1992). They differ in several independent features, are at different ploidy levels (Brochmann et al. 1993), and represent different genomes or combinations of genomes. The typification of the name D. alpina, on a specimen from N Sweden (Elven in Jonsell & Jarvis 2002), connects this name to an amphi-Atlantic decaploid (2n = 80) species. The major confusion in Svalbard has been with the also amphi-Atlantic D. oxycarpa Sommerf. (previously as D. gredinii E.Ekman) but that species is octoploid (2n = 64) and genetically distinctly different (Brochmann et al. 1992), albeit morphologically rather similar, possibly due to sharing some morphologically influential genome(s) with D. alpina. The three other yellow-flowered species are arctic circumpolar: the tetraploid (2n = 32) D. pauciflora, the hexaploid (2n = 48) D. micropetala, and the highly polyploid (14–18×, 2n = ca. 100–144) D. corymbosa.

Draba alpina is now documented from NE Canada, Greenland, Svalbard, the Scandinavian mountains (S and N), and NW Russia. The plants of Iceland and Jan Mayen are still disputed, whether belonging to D. alpina, D. oxycarpa, or to both.

Some populations of Draba from the Colesbukta and Longyearbyen areas (Nordenskiöld Land) deviate from the norm of D. alpina in being more large-grown and with a predominance of stellate or at least dense multibranched hairs on leaves and culms. Both these characters are in common with an enigmatic Russian species, D. glacialis Adams, described from the estuary of Lena River in Siberia and replacing D. alpina east of the Urals. These plants have not been studied genetically and only superficially as to morphology.

Literature

Alsos, I.G., Müller, E. & Eidesen, P.B. 2013. Germinating seeds or bulbils in 87 of 113 tested Arctic species indicate potential for ex situ seed bank storage. – Polar Biology 36: 819–830. Doi 10.1007/s00300-013-1307-7.

Brochmann, C., Borgen, L. & Stedje, B. 1993. Crossing relationships and chromosome numbers of Nordic populations of Draba (Brassicaceae), with emphasis on the D. alpina complex. – Nordic Journal of Botany 13: 121–147.

Brochmann, C., Soltis, D.E. & Soltis, P.A. 1992. Electrophoretic relationships and phylogeny of Nordic polyploids in Draba (Brassicaceae). – Plant Systematics & Evolution 182: 35–70.

Jonsell, B. & Jarvis, C.E. 1994. Lectotypification of Linnaean names for Flora Nordica Vol. 1 (Lycopodiaceae–Papaveraceae). – Nordic Journal of Botany 14: 145–164.