Solitary to mat-forming herb growing in tussocks or dense stands due to horizontal, branched rhizome with short branches (1–3 cm). Base of tussocks densely covered by abundant, 3–5 mm broad, withered leaves and sheaths from previous years, with moderately distinct veins, dull, medium greyish brown. Culms several from each tussock, 5–15(20) cm, with 1–3 prophylls at base (reduced leaves with sheaths only or very short blades), erect but often nodding at top, terete, slightly ribbed, glabrous, bluish or reddish green. Leaves mainly basal; culms with 1–3 leaves, the uppermost much reduced and most often above the middle of the culm.
Leaves flat, canaliculate in apex. Basal leaves 4–7 cm long, 3–5 mm broad, gradually tapering in upper half, with numerous more or less indistinct veins, margins minutely but densely and sharply serrate, especially in upper part of the leaf, glabrous, bluish green or mostly tinged with purple.
Inflorescence an open cyme, 2–3(4) times branched, with flowers singly on short pedicels (up to 5–6 mm) or in groups of 2–3 short-stalked flowers. Inflorescence subtended by numerous short bracts, 4–6(10) mm, oblong, truncate and fringed with numerous ca. 1 mm long hairs, reddish brown with a hyaline apex. Bracteoles ca. 1 mm, orbicular or oblong, obtuse or fringed, dark reddish brown.
Flowers radially symmetric with 6 (3 + 3) tepals. Tepals subequal, 2–2.5 mm, narrowly lanceolate, acuminate, about as long as fruit, blackish red or brown but paler at apex. Stamens 6. Gynoecioum of 3 carpels with 3 stigmas.
Fruit a one-roomed capsule with 3 seeds. Capsule ellipsoid, subacute, with a very short style, brownish black. Seeds 1.0–1.3 mm, without a distinct elaiosome (see L. arcuata).
Sexual reproduction by seeds; local vegetative reproduction by some fragmentation of colonies. Wind pollinated. Flowering is regular in Svalbard but fruit set and seed maturation probably intermittent. Seeds germinated to 20 % in an experiment (Alsos et al. 2013).
Seeds have no adaptation to any special way of dispersal and are probably spread for some distance by wind. Some bird dispersal is possible where the plant grows in moist or wet site types.
As long as one recognizes a Luzula, there is no other species in Svalbard resembling this one with its open inflorescence where the flowers are not congested into heads.
Shallow mires and moist moss tundra, mostly with a dense but not deep moss carpet. In Svalbard confined to fine-grained substrates (often more coarse-grained and sometimes dry in other regions). The soil reaction (pH) is probably circumneutral to slightly acidic; the species is confined to an area with Tertiary sandstones.
Probably thermophilous. Restricted to the middle arctic tundra zone and the weakly continental section. This restriction may, however, be due to its very small range in Svalbard. It is found only on Spitsbergen in a belt across the middle part of the peninsula between Isfjorden and Van Mijenfjorden (in Nordenskiöld Land) and with one locality on the south shore of Van Mijenfjorden (in Nathorst Land).
The global range is arctic–alpine circumpolar but with a gap across Greenland where only a single locality is known (in NE Greenland). The species is rather common in N Fennoscandia and in the arctic Russian regions to the east. The connection of the Svalbard population is to the east and/or south.
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.