Solitary graminoid herb growing in small, dense tussocks with all branching inside the leaf sheaths (intravaginal, e.g., with no runners or stolons). Culms to 10(15) cm, erect, densely pubescent with short, stiff white hairs, especially in the upper (distal) part. Base of culms and leafy shoots surrounded by pale brown sheaths of previous years' leaves. Usually with no prophylls (scaly leaves without a developed blade at base of shoots), sometimes one.

Leaves filiform, narrowly convolute with ribs due to sclerenchyma (discontinuous strings of strengthening tissue), scabrous in margin and along veins. Basal leaves 3–7 cm long, shorter than culms, 0.4–0.6 mm broad. Leaf sheaths open. Uppermost culm leaf (the 'flag leaf') blade linear, 0.5–2(3) cm, attached well below the middle of the culm. Ligula very short (less than 1 mm).

The units of the inflorescence of Poaceae are the spikelets, nearly always numerous in a panicle or spike-like inflorescence. Spikelets are composed of 2 glumes (bracts for the spikelet) and one or more flowers (the term used below) or rather floral units often named ‘florets’ because we do not know what is the exact flower. A flower or floret is composed of a lemma with 1 mid vein (probably the floral bract), a palea with 2 mid veins (either 2 fused bracteoles or perhaps 2 fused perianth leaves), 3 small organs called ‘lodiculae’ and essential in the opening of the flower at anthesis (possibly transformed perianth leaves or transformed stamens), 3 stamens (mostly), and a gynoecium of 2 fused carpels with 2 feathery stigmas and one seed.

Inflorescence a dense, one-sided, ovate, dark purple or purple-brown panicle 1–2 cm long, occupying less than 1/4 of culm length. Panicle branches short (< 5 mm), scabrous due to long, slender spinules, each branch with 1–3 spikelets. Spikelets 7–13 × 1.8–3.0 mm (awns included), with 4–6 flowers. Bracts (glumes and lemmas) with rounded backs. Glumes 3–5 mm, the lower one little shorter than the upper one, acute to acuminate, with 1–3 indistinct veins, glabrous and shiny. Lemmas (excluding awn) 4–6 mm, with a 1.5–2.5 mm awn, with several more or less distinct veins, scabrous, especially in distal part; awn very scabrous. Palea scabrous both on and between veins. Anthers well developed, 0.4–1.1 mm.

Fruit an achene (with one seed).

Sexual reproduction by seeds; no vegetative reproduction. Wind pollination. Seed production abundant (R. Elven observ.), germination about 18 % (Alsos et al. 2013).

Passive dispersal of fruits inside florets, but the scabrous awn may attach to birds and animals and also facilitate some wind dispersal.

The fescues of Svalbard belong to several groups. The Festuca rubra group is characterized by both intravaginal and extravaginal branching, the latter resulting in rhizomatous mats, and by several prophylls (reduced leaves usually without or with short blades) at the base of the shoots. All the others have intravaginal branching only, resulting in dense tussocks without any runners, and only one or no prophyll. The tussocky species are divided on four groups: Festuca baffinensis, the F. brachyphylla group, F. ovina, and the F. vivipara group. Festuca baffinensis and the F. brachyphylla group are both distinguished from F. ovina (and its more southern relatives) by the short anthers (less than 1.2 mm), whereas F. ovina has anthers of ca. 2 mm). Festuca baffinensis differs from the F. brachyphylla group in its hairy culms and its one-sided dark purple panicle; the others have glabrous culms and many-sided and otherwise coloured panicles. The F. vivipara group differs from the other groups in reproduction by bulbils (vivipary).

Aiken et al. (1995) emphasized (in their key) that the ovary apex in F. baffinensis has a few hairs, whereas those of the F. brachyphylla group have no hairs. This character is considered to be of importance in several parts of the genus Festuca but is impossible to observe without special equipment.

Festuca baffinensis grows in meadow slopes and screes, often in species-rich, luxuriant vegetation. All occurrences are within calcareous areas with mainly basic substrates. The substrate is usually moderately coarse (mixed moraine, sand or gravel) and well drained, in sites with short duration of snow cover. The species is an indicator of locally favourable sites (comparatively warm, long season due to early snow-melt, enough moisture but well drained, basic soils). Many other geographically restricted species are usually found together with F. baffinensis.

The Svalbard range of Festuca baffinensis is strongly concentrated to favourable southfacing sites in the calcareous areas along the inner branches of Isfjorden and the arctic steppe areas with basic substrates in Wijdefjorden. More than 80 % of its known occurrences are located at the middle and interior parts of the Isfjorden area (mainly in Sabine, Bünsow and Dickson Lands, but absent from, e.g., the Tertiary sandstones of the Longyearbyen area in Nordenskiöld Land) and the middle and interior parts of the Wijdefjorden area (Andrée and Dickson Lands, Ny-Friesland). Smaller concentrations are found on Ossian Sarsfjellet in Kongsfjorden (Haakon VII Land) and on the bird cliff Wulffberget at Liefdefjorden (also Haakon VII Land). Single sites are found on the high altitude nunatak of Palasset between Kongsfjorden and Isfjorden, in Lomfjorden on the east coast of Spitsbergen (Ny-Friesland), on nunataks at very high levels south of Lomfjorden (in Olav V Land), and on the second largest island of the Svalbard archipelago, Nordaustlandet, at Floraberget in the Murchinsonfjorden area (Gustav V Land) and innermost in Wahlenbergfjorden (Gustav Adolf Land). The range is disrupted but explainable by climatic conditions and the species’ edaphic and climatic demands.

Festuca baffinensis is mainly an arctic species of North America and Greenland, reaching across the North Atlantic to Svalbard and Novaya Zemlya and across the Bering Straits to NE Asia. The ancestral connection of the Svalbard population is probably to the west.

Festuca baffinensis is a morphologically distinct, tetraploid (2n = 28), sexual species somewhat distant from the other major groups of filiform-leaved tussocky fescues in the Arctic, the F. brachyphylla, the F. ovina and the F. vivipara groups, even if it often is assigned to the F. brachyphylla group. Early studies of the F. brachyphylla group in Svalbard (e.g., in the maps and descriptions of Rønning 1972) are misleading. What later has been shown to be the most common species of all, F. edlundiae, was not yet recognized at Rønning’s times. After the elucidating study of Aiken et al. (1995) in North America, the group was studied in Svalbard by S. Fjellheim and A.S. Guldahl. They concluded that the F. brachyphylla group as they circumscribed it (including F. baffinensis), included four species in Svalbard, distinct in morphology, partly cytology, and in the molecular markers studied (Fjellheim 1999, Fjellheim et al. 2001: RAPDs; Guldahl 1999, Guldahl et al. 2001: isozymes). Fjellheim proved some possible hybrids but not involving F. baffinensis. Guldahl found the core F. brachyphylla group (F. brachyphylla, F. edlundiae, F. hyperborea) to have closer affinities in isozymes to F. ovina than to F. baffinensis, i.e., in the investigated markers F. baffinensis was rather isolated from both the core F. brachyphylla group and from F. ovina.

Aiken, S.G., Consaul, L.L. & Lefkovitch, L.P. 1995. Festuca edlundiae (Poaceae), a high arctic, new species compared enzymatically and morphologically with similar Festuca species. – Systematic Botany 20: 374–392.

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.

Fjellheim, S. 1999. RAPD DNA and morphological variation in seminiferous taxa of the Festuca brachyphylla complex (Poaceae) in Svalbard. – Cand. scient. thesis, Univ. Oslo, Oslo.

Fjellheim, S., Elven, R. & Brochmann, C. 2001. Molecules and morphology in concert. II. The Festuca brachyphylla complex (Poaceae) in Svalbard. – American Journal of Botany 88: 869–882.

Guldahl, A.S. 1999. The Festuca brachyphylla complex in Svalbard: enzymatic, chromosomal, and ecological variation. – Cand. scient. thesis, Univ. Oslo, Oslo.

Guldahl, A.S., Borgen, L. & Nordal, I. 2001. Variation in the Festuca brachyphylla (Poaceae) complex in Svalbard, elucidated by chromosome numbers and isozymes. – Botanical Journal of the Linnanean Society 137: 107–126.

Rønning, O.I. 1972. The distribution of the vascular cryptogams and monocotyledons in Svalbard. – Det Kongelige Norske Videnskabers Selskabs Skrifter 1972-24. 63 pp.