Life span

Perennial, moderately long-lived.

Growth form

Solitary graminoid herb growing in dense tussocks with all branching inside leaf sheaths (intravaginal, i.e., no runners or stolons). Culms 5–20(30) cm, erect, smooth in lower parts, often with dense, short, stiff hairs beneath the panicle. 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.

Leaf

Leaves filiform, narrowly involute, with discontinuous strings of sclerenchyma (strengthening tissue) making leaves more or less angled (with ribs) in cross-section, with scattered, stiff hairs on ribs. Basal leaves 2–8(10) cm long, often ca. 1/2 length of culms, narrow, 0.4–0.8 mm. Leaf sheaths open for much of their length. Culm leaves filiform; uppermost leaf (the 'flag leaf') blade 1.5–3(4) cm, attached at the middle of culm or below. 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, 1.5–4 cm long, occupying less than 1/3 of culm length. Panicle branches short, 2–4 mm, at 4–6 nodes, one at each node. Branches rough due to dense, short, stiff hairs, each normally with 1 spikelet. Spikelets deformed by bulbil production, probably with 2–4 flowers initially, but untransformed flowers usually absent (and not possible to measure). Bracts (glumes and lemmas) with rounded backs (no keel) and 1–several indistinct veins. Glumes lanceolate, 3–4 mm, the lower slightly shorter than the upper, acute but without awn, shiny, glabrous in proximal part, slightly scabrous in distal part, fringed by short, stiff hairs in upper part and apex. Lemmas (when not transformed) 4–6 mm, lanceolate, acute but without awn, shiny, scabrous to sparsely stiff pubescent in distal part. Stamens not observed; anthers noted from other regions to be ca. 2 mm long.

Fruit

All flowers in the spikelet replaced by a single, leafy bulbil (vivipary).

Reproduction

Asexual reproduction by bulbils only. Bulbil production is abundant in Svalbard, and they sprout to near 100 % both when put in moist conditions in autumn (I.G. Alsos observ.) and after one winter of storage at -14°C (Alsos et al. 2013). Whereas most bulbils are shed in autumn and have short dispersal distance, some last until winter and might be spread over longer distance by wind over a smooth surface of snow. Whether this species ever has any seed-set is undecided (Frederiksen 1981), and any seed-set is probably not resulting in any reproduction.

Bulbils are very efficient in reproduction and partly in dispersal. Frederiksen (1981) noted that bulbils (in Festuca) have 10 times the weight of seeds in the same or closely related species, i.e., they carry much more nutrients for early development, are already green with a chlorophyll apparatus and photosynthesis well developed, often with roots emerging before they leave the panicle, and that this makes for very rapid and efficient establishment of new plants under favourable conditions. In a cultivation experiment in the field in the middle alpine belt at Finse, S Norway, the viviparous Poa alpina var. vivipara developed from bulbil to reproducing plant within one year, whereas the seminiferous var. alpina took three years or more from seed to reproducing plant (Elven 1974). It is no reason to assume that viviparous species of Festuca are significantly different.

Frederiksen (1981) stated that bulbils of Festuca vivipara probably dry out more easily than seeds and are spread only over short distances. However, elsewhere in her paper she points to the spread of just this species to the highly isolated oceanic islands of Jan Mayen and Bjørnøya, which vouch for a fairly good dispersal ability. In a largely unpublished study, L. Ryvarden showed that bulbils are very efficiently spread by wind across snow or even across mid-size ice-caps, and they keep their sprouting ability even after very rough handling across glaciers (across the Hardangerjøkulen ice-cap in S Norway). The bulbil collection in his study included F. vivipara besides Deschampsia alpina and two Poas. Bulbils do not depend much on good weather for establishment; they usually develop whatever the conditions may be and very often sprout on the plant after a winter under snow cover (R. Elven observ., Hardangerjøkulen area).

Comparison

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 possible to observe 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 vs. hairy leaves in F. ovina (in Svalbard). The glumes and lemmas of the F. vivipara group are narrowly lanceolate, almost linear, and the lemmas are without awns vs. the more broadly lanceolate glumes and lemmas and the awned lemmas in F. baffinensis, the F. brachyphylla group, and also F. ovina.

Differences from F. rubra are rather 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. viviparioidea. 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). Festuca frederikseniae (in the Svalbard meaning) 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, making them more or less angular in cross-section. This feature 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.

Habitat

Usually on open ground or in gaps in discontinuous vegetation, on coarse to moderately coarse, usually well-drained substrates (stones, gravel and sand). The species is most frequent on substrates with acidic to circumneutral soil reaction (pH). It is also found in areas with basic bedrock but rarely on directly calcareous soils. It probably needs some snow cover in winter.

Distribution

Festuca viviparoidea occurs in all zones and sections. It is recorded from all the major islands in the Spitsbergen group and also from Prins Karls Forland and Kong Karls Land. Not occurring on Bjørnøya (but  F. vivipara s. str. is present there). As seen from the map, there are concentrations of localities along the middle and inner parts of the major fjords on Spitsbergen: Van Mijenfjorden, Isfjorden, Wijdefjorden, and Liefdefjorden, and it is conspicuously rare in the very well explored Kongsfjorden area. This is a rather visible and easily recognizable plant and the pattern is probably real. The central parts of the Kongsfjorden area are rather calcareous, and this may be a reason for the rarity of this species.

Outside Svalbard, this is the most widespread arctic plant of this group, with one part of the distribution in the North Atlantic regions from N Greenland eastwards to Taimyr (Frederiksen 1981; Malyschev & Peschkova 2001) and another in the North Pacific regions in Chukotka, Alaska, and W Canada (Frederiksen 1981; Soreng 2007). The two gaps in this range are huge, 80° from Greenland to the Yukon Territory and 75–80° from Taimyr to Chukotka. Elven et al. (2011) suggested that the two parts of the range are occupied by two different species, perhaps with different combinations of parental species. This suggestion has some support in a difference in reported chromosome numbers (see Comments).

Comments

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 hybrids within the more temperate F. ovina s. lat., between F. ovina s. lat. and the arctic F. brachyphylla group, or 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 along the St. Lawrence gulf in E Canada (but see our F. aff. 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.

Literature

Alexeev, E.B. 1985. Ovsyanitsii (Festuca L., Poaceae) Alyaski i Kanadii. – Novosti Sistematiki Vysshykh Rastenii 22: 5–36.

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 Biology36: 819–830. Doi: 10.1007/s00300-013-1307-7.

Elven, R. 1974. Artsinnvandring og vegetasjonsutvikling på resente morener i Finseområdet. – Cand. real. Thesis, Univ. Oslo, Oslo.

Elven, R., Murray, D.F., Razzhivin, V. & Yurtsev, B.A. (eds.) 2011. Annotated Checklist of the Panarctic Flora (PAF).

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

Flovik, K. 1938. Cytological studies in arctic grasses. – Hereditas 24: 265–376.

Frederiksen, S. 1981. Festuca vivipara (Poaceae) in the North Atlantic area. – Nordic Journal of Botany 1: 277–292.

Malyschev, L.I. & Peschkova, G.A. (eds.) 1990. Flora Sibiri. 2. Poaceae (Gramineae). – Nauka, Novosibirsk.

Pavlick, L.E. 1984. Studies on the Festuca ovina complex in the Canadian Cordillera. – Canadian Journal of Botany 62: 2448–2462.

Salvesen, P.H. 1986. Festuca vivipara in Southern Norway, infraspecific differentiation and systematic affinities. – Symbolae Botanicae Upsaliensis 27(2): 155–167.

Soreng, R.J. 2007. Poa L. – In: Flora of North America Editorial Committee (eds.), Flora of North America north of Mexico 24. Magnoliophyta: Commelinidae (in part): Poaceae, part 1: 486–601.