Solitary graminoid herb growing in very dense, usually small tussocks with all branching inside leaf sheaths (intravaginal). Roots characteristically curled. Basal sheath cylinders dense, straw-coloured, with marked, yellowish veins. Aerial shoots with 2–3 prophylls (basal, reduced leaves without or with only a short blade). Culms 4–10(12) cm, spreading, more rarely erect, smooth and glabrous, with 1–2 leaves. The shoots often skewed to one side in smaller tussocks or spreading radially from the centre of larger tussocks, looking like they have been trampled on.

Leaves 1.5–5 cm long, about half as long as culms in well developed plants, flat or moderately folded, keeled and with apex like the prow of a boat, with veins on the upper surface broad and distinctly raised, on the lower surface narrow and less distinctly raised, smooth and glabrous, yellowish green or reddish. Ligula (1)1.5–2 mm, obtuse or acute.

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 contracted, narrowly oblong to oblong, small panicle, up to 3–4 × 1–1.5 cm, occupying ca. 1/2–1/4 of culm length. Panicle with 3–6 nodes with 2–3 branches at each of the lower nodes. Branches erect or erectopatent, 5–20 mm, smooth, each with 1–7 spikelets along much of their length. Spikelets 5–8 × 1.5–2.5 mm, with 4–6 flowers. Bracts (glumes and lemmas) with rounded backs. Glumes usually subequal (the lower slightly shorter and narrower than the upper, rarely much shorter), 2.5–4.5 × 0.8–1.2 mm, about as long as the lower lemmas, firm, narrowly oblong or obovate, apex rounded or subacute, uneven but rarely lacerate, not ciliolate (i.e., without small, single-cell teeth), with 3–5 distinct, sometimes rib-like veins, smooth and glabrous, violet, sometimes green on and near the mid vein and with a narrow golden yellow and white hyaline margin and tip. Lemmas 2.5–4.5 × 1.5–2.2 mm, narrowly oblong, obtuse or subacute, apex irregular or slightly lacerate, with 5(7) veins, with long hairs on the proximal half of the veins, otherwise smooth and glabrous, violet with a broad golden yellow and white hyaline margin and tip. Paleas shorter than lemmas, with veins with intertwined hairs in their proximal part, scabrous in their distal part. Anthers ca. 1 mm.

Fruit an achene (with one seed).

Sexual reproduction by seeds; no vegetative reproduction. Wind pollinated. Seed-set is regular in Svalbard. Seeds germinate to 52 % in an experiment (Alsos et al. 2013).

Fruits (spread inside florets) have no special adaptations to dispersal, probably mainly by wind, surface water and birds.

The species of Puccinellia can be mistaken for Poa but differ in having no keel on glumes or lemmas but rather an evenly rounded back. They also differ in lemmas broad nearly to the apex, often truncate, rounded or subacute with apex uneven, lacerate or fringed, whereas all Poa have lemmas tapering gradually towards a usually acute apex and usually entire in the margin (however, the lemmas of Poa abbreviata, P. glauca and P. hartzii may have lacerate apices).

The genus Puccinellia is notoriously difficult and with numerous species in the Arctic, many of them endemic (restricted) to the arctic regions. They are difficult also in Svalbard. We here recognize 5 species but there may be more (especially in the affinity of P. angustata).

Puccinellia phryganodes differs from all the others in being stoloniferous and asexual with aborting flowers (look for shrivelled anthers) and little flowering; all the others are tussocky, sexual and always abundantly flowering. For the unmistakeable stolons of P. phryganodes, see that species.

Puccinellia angustata and P. vahliana both have paleas with intertwined hairs on the proximal parts of the veins (keels), whereas P. coarctata and P. svalbardensis have no intertwined hairs on palea keels. Puccinellia vahliana differs most distinctly from P. angustata in the glumes. In P. vahliana they are mostly subequal, the longest about the same length as the lower lemmas, and firm; in P. angustata they are unequal, both much shorter than the lower lemmas, and flimsy.

Puccinellia svalbardensis differs from (arctic) P. coarctata most distinctly in the shape of the panicle. The panicle of P. svalbardensis is very open with very slender, spreading to patent or even retrorse, long branches; that of P. coarctata is more contracted with stouter, erect or erectopatent branches. The keels (veins) of the paleas in P. svalbardensis are smooth, those of P. coarctata scabrous at least in their distal parts. In addition, the lemmas of P. svalbardensis are lacerate, whereas those of P. coarctata are distinctly ciliolate (with one-celled teeth). Mistaking these two species is, however, impossible in practice in Svalbard as P. coarctata is a seashore species restricted to Bjørnøya, whereas P. svalbardensis mainly is an arctic steppe species and restricted to northern parts of Spitsbergen.

Puccinellia vahliana is mainly found on patterned ground and on open patches in not too wet moss tundra and moist heaths, usually on fine-grained substrates (with a good water capacity) but sometimes on gravel. It is basiphilous, never found on acidic substrates and rarely on circumneutral ones (e.g., absent from the Longyearbyen – Adventdalen area with Tertiary sandstones).

Cryophilous. In the middle and northern arctic tundra zone and the transitional to clearly continental sections. This species is restricted to Spitsbergen, Nordaustlandet, Prins Karls Forland (Fuglehuken), and one site on W Edgeøya. It may have been overlooked on Edgeøya and Barentsøya. It is widespread in Spitsbergen, from Sørkapp Land to the north coast, but with evident concentrations to areas with calcareous substrates at inner Isfjorden (Sabine, Bünsow and Dickson Lands), inner Wijdefjorden (Andrée Land and Ny-Friesland), Kongsfjorden (Oscar II and Haakon VII Lands) and Liefdefjorden (Haakon VII Land). On Nordaustlandet, it is known from several areas but mainly in the more sheltered fjord districts, not reaching the polar desert zone.

Puccinellia vahliana is mainly a western arctic species, common through the more northern zones in Canada (with a very few finds in Alaska), common in N Greenland, and extending across the North Atlantic to Svalbard and Novaya Zemlya.

Puccinellia vahliana belongs to the section Pseudocolpodium, otherwise including a few Beringian and N Siberian species: P. byrrangensis Tzvelev in Taimyr, P. wrightii (Scribn. & Merr.) Tzvelev in the amphi-Beringian areas, and perhaps two species more, one on Wrangel Island (Russian Far East, P. colpodioides Tzvelev) and another on Banks Island (Canada, possibly still undescribed). This section has several characters distinguishing it from the other parts of Puccinellia, a reason why it previously was considered belonging to another genus: Colpodium. It has, however, been shown that these species belong within Puccinellia, whereas Colpodium s. str. is a genus of the C Asian mountains. The name Colpodium was, for a long time, applied to the Svalbard plant (e.g., Rønning 1963, 1964, 1972, 1979) and is still applied by some. Also Pucciphippsia vacillans (see that species) was assigned to Colpodium and is a genus hybrid between Phippsia algida and Puccinellia vahliana. The only other species assigned to Pucciphippsia (Pucciphippsia czukczorum) has its origin from Phippsia algida and another species of sect. Pseudocolpodium, perhaps P. wrightii. This, in addition to the molecular studies (see Steen 2004), suggests that sect. Pseudocolpodium may be the connecting link between the genera Puccinellia and Phippsia.

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.

Rønning, O.I. 1963. The Spitzbergen species of Colpodium Trin., Pleuropogon R. Br., and Puccinellia Parl. – Kongelige Norske Videnskabers Selskabs Skrifter 1961-4. 50 pp.

Rønning, O.I. 1964. Svalbards flora. – Norsk Polarinstitutt, Oslo.

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

Rønning, O.I. 1979. Svalbards flora. Ed. 2. – Norsk Polarinstitutt, Oslo.

Steen, N.W., Elven, R. & Nordal, I. 2004. Hybrid origin of the arctic X Pucciphippsia vacillans (Poaceae): evidence from Svalbard plants. – Plant Systematics & Evolution 245: 215–238.