Characters of the panicle and flowers are mainly described on specimens from Jan Mayen as nearly all specimens available from Svalbard (Bjørnøya) have stunted, badly developed panicles.
Solitary graminoid herb growing in dense or loose tussocks with all branching inside leaf sheaths (intravaginal, i.e., no runners or stolons). Culms to 8 cm (normally to 15−20 cm outside Svalbard), erect, smooth in lower parts, scabrous beneath the panicle with often dense, short, stiff hairs. Base of shoots densely surrounded by shiny, pale straw-coloured, withered leaf sheaths. No prophylls (scaly leaves without a developed blade at base of leafy and reproductive shoots) or one.
Leaves filiform, narrowly convolute, with a continuous sheet of sclerenchyma (strengthening tissue) making leaves terete (without or with only indistinct ribs) in cross-section, glabrous and smooth. Basal leaves 3−4 cm long (much longer outside Svalbard), shorter than culms, narrow, 0.5−1.0 mm. Leaf sheaths open for much of their length. Culm leaves filiform; the uppermost leaf (the 'flag leaf') blade up to 2.5 cm, attached at the middle of culm or above. Ligula very short (less than 0.5 mm), truncate.
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’ being essential in the opening of the flower at anthesis (possibly transformed perianth leaves or transformed stamens).
Inflorescence an elongate, fairly dense, one-sided panicle, 1.5−3 cm long, occupying less than 1/3 of culm length. Panicle branches short, 3−4 mm, at 4−6 nodes, 1 at each node. Branches rough due to dense, short, stiff hairs, each normally with 1 spikelet (in Svalbard plants). Spikelets 4−6 × 1−2 mm, with 3−4 flowers (in Svalbard). The spikelets usually have 1−2 untransformed flowers in their lowermost parts, with ovules and often anthers. Bracts (glumes and lemmas) with rounded backs and 3−several distinct veins. Glumes slightly unequal, the lower slightly shorter than the upper, 3−4 mm, narrowly lanceolate, narrowly acute but without awn, shiny, glabrous in their proximal part, scabrous to pubescent in their distal part, often fringed with hairs. Lemmas 3−4 mm, narrowly lanceolate, narrowly acute but without awn, short pubescent but not densely pilose. Stamens (if present) 3; anthers ca. 2 mm long.
No seed-set observed in Svalbard plants; perhaps a few seeds observed elsewhere, see Frederiksen (1981), but seed-set obviously extremely rare and probably not resulting in any reproduction. One of more flowers in the spikelet replaced by a single, leafy bulbil (vivipary).
Asexual reproduction by bulbils only. For more information on bulbil reproduction and dispersal, see Festuca viviparoidea. Bulbil production is abundant in other regions but none of the studied Svalbard plants had developed mature bulbils, only observed with largely aborting panicles. We still assume that bulbils are produced and establish new plants now and then.
Grasses that regularly reproduce by bulbils (vivipary) in Svalbard belong to three genera: Deschampsia, Festuca and Poa. All viviparous Deschampsia and Festuca are tussock-forming with intravaginal branching only, whereas all viviparous grasses with extravaginal branching and rhizome systems (mat-forming) belong to Poa. Deschampsia alpina is distinguished from Festuca and Poa by much stouter leaves with raised veins on the upper surface (often hidden because the leaves are convolute), shiny hyaline glumes and lemmas, and spikelets with only two flowers (the two other genera have spikelets with several flowers). Viviparous Festuca and Poa are easily kept apart by the former having filiform leaves and acute glumes with rounded back, the latter having flat or folded leaves and broadly ovate glumes with keel.
The Festuca vivipara group (F. frederikseniae, F. vivipara, F. viviparoidea) differs from the other tussock-forming species of Festuca in Svalbard (F. baffinensis, the F. brachyphylla group, F. ovina) in being viviparous with panicles with bulbils developed instead of fruits. The elongation and transformation of the lemmas into the leaves of the bulbils is observable rather early in the flowering season. Where developed panicles are not available, the species may be more difficult to distinguish but the following characters can be used. The F. vivipara group has glabrous leaves, whereas F. ovina (in Svalbard) has hairy leaves. The glumes and lemmas of the F. vivipara group are narrowly lanceolate, almost linear, and the lemmas are without awns, compared with the more broadly lanceolate glumes and lemmas and the awned lemmas in F. baffinensis, the F. brachyphylla group, and also in F. ovina.
Differences from F. rubra are more evident. Festuca rubra always have some branching outside the leaf sheaths (extravaginal), whereas all branching in the F. vivipara group (and in the other tussocky species) is intravaginal. The flag leaf and sometimes also basal leaves are often more or less flat in F. rubra, always filiform and densely convolute in the tussocky species. The leaf sheaths are closed nearly up to the blade, and with distinct auricles at the transition between sheath and blade in F. rubra, open for a major part of their length and without distinct auricles in all the others.
The differences between the three species of the F. vivipara group are more subtle but their distributions in Svalbard are rather different. Festuca vivipara is the only species of this group on Bjørnøya, F. frederikseniae is at present only known from a single locality at Dicksonfjorden on Spitsbergen, whereas all other plants in Svalbard currently are assigned to F. viviparoidea. There are some morphological differences considered to be taxonomically important, even if they are not always readily observed. Festuca vivipara (and F. ovina) has a continuous sheet of schlerenchyma in the leaves, making leaves terete in cross-section (a lens with strong magnification or a microscope is necessary). Svalbard specimens of Festuca frederikseniae, and F. viviparoidea (and F. baffinensis and the F. brachyphylla group) have discontinuous sclerenchyma resulting in slight to distinct ribs on the surface of the leaves, creating a more or less angular in cross-section. This angular cross-section is also found in F. rubra and in possible hybrids between that species and F. ovina. The most easily observed difference between the three species of the F. vivipara group is found in the lemmas. The lemmas of F. vivipara are normally greyish green or pale violet and pubescent with short, stiff hairs; those of F. viviparoidea are greyish violet or purple, and smooth and glabrous, at least in their lower parts; and those of F. frederikseniae are greyish violet and densely pilose.
Information from the few herbarium sheets available (translated here from Norwegian): frost polygons, centre of soil polygons. Festuca vivipara seems to occur mainly (or only) on moist, frost-influenced tundra. Engelskjøn & Schweitzer (1970: 7): "It is copious on naked solifluction soil in Devonian−Culm, as well as in limestone areas."
In Svalbard, Festuca vivipara is restricted to Bjørnøya where it is rather common (Engelskjøn & Schweitzer 1970, with 17 mapped sites). This is the middle arctic tundra zone and the weakly oceanic section.
Outside Svalbard, this is the major species within this group in the North Atlantic regions, common in most parts of W Scandinavia, the N and W British Isles, Iceland, SE Greenland (south of the range of F. viviparoidea there, with almost no overlap, see Frederiksen 1981), and the arctic islands of Jan Mayen and Bjørnøya. It is also reported from northernmost Polar Ural and S Novaya Zemlya in European Russia (Frederiksen 1981; Tolmachev et al. 1995; but refuted by Malyschev & Peschkova 2001).
Bulbil-reproducing grasses (vivipary) are usually assumed to be an 'escape' from sterility in hybrids, either hybrids between incompatible lines within species (as in Poa alpina, perhaps between different chromosome number races) or between species (as in, e.g., Deschampsia alpina, Festuca spp., Poa jemtlandica, and perhaps the P. arctica/pratensis complex). Frederiksen (1981) assumed the viviparous species of Festuca to be: 1) hybrids within the more temperate F. ovina s. lat., 2) between F. ovina s. lat. and the arctic F. brachyphylla group, or 3) between any of these groups and F. rubra s. lat.
Frederiksen described the F. vivipara group as three subspecies of one species (F. vivipara) based on cytological and morphological evidence: ssp. vivipara in more temperate North Atlantic regions but reaching north to SE Greenland, Jan Mayen and Bjørnøya; ssp. hirsuta (Schol.) Fred. in SE and SW Greenland, Newfoundland and Labrador, and by the St. Lawrence gulf in E Canada (but see our F. frederikseniae for a Svalbard complication); and ssp. glabra Fred. in the high arctic regions, with one part area in NE and N Greenland, the Spitsbergen group, and NW Russia, and another in NE Asia, Alaska and W Canada. She found correlations between morphology and chromosome number levels. Her ssp. vivipara and ssp. hirsuta were tetraploids (2n = 28), her Atlantic ssp. glabra hexaploid (2n = 42), and her Pacific ssp. glabra octoploid (2n = 56). She considered Atlantic triploids (2n = 21) to be hybrids between the diploid F. ovina s. str. and the tetraploid F. vivipara ssp. vivipara. Subsequent studies have rather suggested that both triploids and tetraploids occur within F. vivipara subsp. vivipara without any other observable morphological difference, and partly outside the range of one of the assumed parents (F. ovina), see Salvesen (1986). Only one chromosome count is known from the main Svalbard plant (ssp. glabra = F. viviparoidea): 2n = 49 (i.e., 7-ploid; Flovik 1938).
Several authors have been reluctant to apply the concept of subspecies for these entities as they probably combine different sexual species in their parentages, i.e., they are independent new lineages. This means, in formal terms, that F. vivipara s. lat. is taxonomically polyphyletic. American and Russian authors (Pavlick 1984; Alexeev 1985; Soreng 2007) have rather accepted Frederiksen's subspecies as three species: F. vivipara s. str. (= F. vivipara ssp. vivipara), F. frederikseniae E.B.Alexeev (= F. vivipara ssp. hirsuta), and F. viviparoidea Krajina ex Pavlick (= F. vivipara ssp. glabra).
The most deviant subspecies of the group is ssp. glabra with its discontinuous leaf sclerenchyma and high ploidy levels (2n = 42, 49, 56), compared with the continuous sclerenchyma and low ploidy levels (2n = 21, 28) of ssp. vivipara and ssp. hirsuta. This might suggest that the diploid F. ovina may be part of the parentage of F. vivipara s. str. and F. frederikseniae but not of that of F. viviparoidea. Elven et al. (2011) discuss this matter further and consider whether the hexaploid and heptaploid, amphi-Atlantic plants of F. viviparoidea (including the plants of the type area for the name) really should be merged with the disjunct, octoploid, amphi-Bergingian plants currently going by the same name.
As for ploidy levels of the Svalbard plants, the few counts available support the solution of two species. The Bjørnøya plants are tetraploid (2n = 28, Engelskjøn & Schweitzer 1970), the Spitsbergen plants probably hexaploid (2n = 42, Frederiksen 1981) and heptaploid (2n = 49, Flovik 1938). The morphology of the three Svalbard plants is also rather different (see above).
One of the issues touched on but not explored by Frederiksen is the relationship of the F. vivipara group, and especially F. viviparoidea, with the mainly arctic F. brachyphylla group. As stated above, anther length is a crucial character for separation among the seminiferous species. The more temperate F. ovina and several relatives in Europe, Asia and North America have anthers ca. 2 mm; the F. brachyphylla group has anthers 0.8−1.2 mm. The plants of the F. vivipara groups often have a few intact flowers at the base of the spikelet, and these uniformly have long anthers (ca. 2 mm). Even if involvement of the F. brachyphylla group in the parentage of parts of the F. vivipara group is not improbable for geographical reasons, it has not yet been proved. We find the differences between the Svalbard representatives of the F. vivipara and F. brachyphylla groups to be rather well marked, and especially the difference in anther length.