Life span

Perennial, moderately long-lived.

Growth form

Solitary herb with subterranean vertical, branched caudex, each caudex branch ending in a rosette at ground level. Flowering stems erect, 10–15(25) cm, single or often several per plant.

Leaf

Leaves alternate, either all basal or a single leaf subtending the lowermost branch of the inflorescence, with petioles (1.5)2–7(10) cm, 2–3 times the length of the blades. Blade (1.0)1.3–2.5(3.0) × 1.5–3.0(3.5) cm, reniform or oblate, about as broad as long or broader, with irregular but not dentate margin, thick, glabrous, and palmate-veined. Leaves are edible and have a nice, acid taste (oxalic acid).

Inflorescence

Inflorescence a terminal, irregular panicle with numerous clusters of 2–5 flowers along each branch, each cluster subtended by a minute, hyaline bract.

Flower

Some plants male, some female, and some with both types of flowers; sometimes also bisexual flowers occurs. Flowers radially symmetric. Floral leaves tepals, i.e., not differentiated into sepals and petals, 2 broad and 2 narrow, in female flowers 2–3 × 1.5–1.6 and 1.5–2 × 0.7–0.8 mm, in male flowers (1.8)2.0(2.2) × 1.6–1.8 and 1.6–1.8 × 0.5–0.6 mm, obovate, pink or green, with usually 3 indistinct veins, attached to the fruit until mature. Stamens 6, with red or yellowish anthers. Gynoecium of two fused carpels.

Fruit

A flat nut with a very broad, green, pink, or red wing. One plant usually produces tens, sometimes hundreds, of nuts.

Reproduction

Sexual reproduction by seeds; no vegetative reproduction. The species flowers throughout much of the summer. The flowers are wind pollinated and adapted to such but some insect pollination may take place. The seed production is high also when self pollinated. Germination varies from 20 to 90 % (tested at 20ºC), but is low (< 1%) when germinated outdoor (Alsos et al. 2013; Hagen 2002; Müller et al. 2011).

The winged nuts are relatively heavy but adapted to wind dispersal, probably mainly along the ground and on snow as they are too heavy to fly high. Downstream water dispersal is also highly probable as the populations often are concentrated along water-courses.

Comparison

There is no similar species in Svalbard.

Habitat

Nearly confined to moderately vegetated, moist or wet sites such as snowbeds in poorly drained depressions, along watercourses, and moist frost patterned ground. Also occurring in other places with stable water supply, e.g., basal parts of screes and bird cliff meadows. On poorly drained, mixed or fine textured soils. Indifferent as to soil reaction (pH) but perhaps more common in acidic areas. Grazed by reindeer and geese.

Distribution

Common in all zones and sections. Recorded from all major islands (incl. Bjørnøya) and common, at least on Spitsbergen.

The general range is circumpolar and arctic–alpine and the species is very widespread, south to the southern Rocky Mountains, C Asia and S Europe.

Comments

Oxyria digyna has no close relatives in the Arctic or in the majority of temperate mountain ranges. Its few relatives in the small genus Oxyria are found in C Asia, China, and the Himalayas.

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.

Hagen, D. 2002. Propagation of native Arctic and alpine species with a restoration potential. – Polar Research 21: 37–47.

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.