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Life span

Perennial, moderately long-lived.

Growth form

Solitary graminoid herb growing in small, dense or loose tussocks, with all branching inside leaf sheaths (intravaginal). Roots not curled. Basal sheaths pale straw-coloured, with strong, pale veins, in dense or loose cylinders. Aerial shoots with 1–3 prophylls (basal, reduced leaves without or with only a short blade). Culms 5–10 cm, ascending or spreading, smooth and glabrous, with 2–3 leaves.

Leaf

Leaves 4–8 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, green or purplish tinged. Ligula 0.8–1.2 mm, apex rounded or sometimes uneven or slightly lacerate.

Inflorescence and Flower

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 an open panicle, up to 3 × 1.5 cm, usually occupying 1/3–1/4 of culm length. Panicle with 4–6 nodes with mostly 1–3 branches at each of the lower nodes. Branches ascending or spreading, 8–15 mm, scabrous, each with 1–5(6)  spikelets, mainly in their distal half. Spikelets 4–6 × 1.3–2.1 mm, with 3–5 flowers. Bracts (glumes and lemmas) with rounded backs. Glumes unequal, both much shorter than the lower lemmas, smooth and glabrous, flimsy. Lower glume 0.8–1.2 × 0.5–0.7 mm, broadly ovate or oblong, obtuse or rounded, apex entire or slightly lacerate or ciliolate (with one-cell teeth), with 3 veins, pale green or pale violet with a broad, white hyaline margin; upper glume 1.4–1.6 × 0.8–1.1 mm, oblong, subacute, with 3 veins, same coloration and apex as lower glume. Lemmas 2–3 × 0.8–1.3 mm, oblong, apex obtuse or truncate and ciliolate, with (5)7 indistinct veins, smooth and glabrous (no hairs on veins), pale violet (often pale green proximally), without distinct hyaline margin. Paleas as long as lemmas, with veins scabrous in their distal 1/2–2/3. Anthers 0.6–0.8 mm.

Fruit

Fruit an achene (with one seed).

Reproduction

Sexual reproduction by seeds; no vegetative reproduction. Wind pollinated. Seed set is observed in Svalbard.

Fruits (inside florets) have no special adaptations to dispersal but are spread almost exclusively by ocean currents.

Comparison

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. corarctata 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.

Habitat

A nearly obligate seashore species, growing in crevices on coastal cliffs, on shore terraces, and on gravelly and sandy shores where algal remains (drift material) is deposited.

Distribution

Thermophilous. Known from several sites along the coasts of Bjørnøya (middle arctic tundra zone, weakly oceanic section). The species was included with P. phryganodes in the map of Engelskjøn & Schweitzer (1970). It was first identified in the Bjørnøya material in the 1990s.

This is a widely distributed, North Atlantic seacoast species, common in NE North America, Greenland, Iceland (we think), Jan Mayen, Bjørnøya, N Fennoscandia, and NW European Russia.

Comments

Puccinellia coarctata belongs to the complicated P. distans group where opinions differ very much about how many species should be recognized and where the species limits should run (as evident from the selected synonymy given above). European authors almost uniformly distinguished between the mainly inland P. distans (Jacq.) Parl. and the coastal P. capillaris (Lilj.) Jansen (= P. retroflexa (Curtis) Holmb.), and have related P. coarctata to the latter, either as a closely related species or as a race (ssp. borealis), following Holmberg's (1926) recognized the N Scandinavian plant of P. capillaris/retroflexa as a separate race, ssp. borealis. Subsequent researchers have rather synonymised Holmberg's race with the NE North American P. coarctata, described from Newfoundland. This was more or less the accepted solution until North American authors merged several species under the W North American name P. nutkaënsis, probably based on molecular studies. This procedure was the one applied by Davis & Consaul (2007) for Flora of North America and by Elven in Lid & Lid (2005) for Norway (and Svalbard). However, a comparison made later between North Atlantic plants and the true Pacific P. nutkaënsis does not support this merger. We have therefore reverted to the Atlantic name P. coarctata, which certainly refers to our plant.

The occurrence of P. coarctata on Bjørnøya is not surprising. This is one of the most commonly found plants on seashores of the North Atlantic, reaching every small island without any problems. Its restriction northwards, i.e., why it has not (yet) been found on Spitsbergen, is probably its demands as concerns length of season and temperatures. Even if it is a hardy plant that reaches far north in Greenland and European Russia, and is present and well developed on Jan Mayen, the Bjørnøya plants flower late in the season and probably do not set seed every year.

Literature

Davis, J.I. & Consaul, L.L. 2007. Puccinellia Parl. – In: Flora of North America Editorial Committee (eds.), Flora of North America north of Mexico. 24. Magnoliophyta: Commelinidae (in part): Poaceae, part 1: 459–477.

Engelskjøn, T. & Schweitzer, H.J. 1970. Studies on the flora of Bear Island (Bjørnøya). I. Vascular plants. – Astarte 3: 1–36.

Holmberg, O.R. 1926. Gramineae. – Hartmans handbok i Skandinaviens flora 2 (pp. 161–320). – P.A. Nordsted & Söners Förlag, Stockholm.