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Life span

Perennial, long-lived.

Growth form

Solitary graminoid herb growing in dense, often large tussocks with all branching inside leaf sheaths (intravaginal, i.e., no runners). Culms to 30 cm, erect, smooth and glabrous. Base of shoots densely surrounded by a sheath of pale, straw-coloured, marcescent leaf remains. Prophylls (scaly leaves without developed blade at base of shoots) 1–2, hyaline.

Leaf

Leaves tapering towards apex, with 5–10 veins, distinct on the lower surface, raised as pale ribs on the upper surface, smooth or slightly scabrous on upper surface. Basal leaves of aerial shoots 8–20 cm long, 0.5–2 mm broad, moderately involute (margins rolled inwards), much shorter than culms. Culm leaves 2–3, often flat, 3–10(14) cm long, 0.8–2.0 mm broad, distinctively decreasing in length upwards on culm, flag leaf blade attached at middle of culm or above. Ligula long, 1.5–6.5 mm, acute, entire.

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. Several of these parts are transformed in grasses propagating by bulbils.

Inflorescence an open panicle 5–12 cm long, occupying 1/2–1/3 of culm length, with ascending to spreading branches. Panicle with 6–10 well separated nodes and 3–6 branches at each of the lower nodes. Branches 20–60 mm, smooth, each with 3–6 spikelets. Spikelets difficult to measure due to vivipary (increasing dramatically in size during growth of bulbils); size before bulbil development 4–6 × 1.0–1.4 mm, with 2(3) flowers. Bracts (glumes and lemmas) with rounded backs. Glumes lanceolate, acute to acuminate or with lacerate apex, lower glume 3.5–4.5 mm, upper glume 4.5–5.5 mm, as long as spikelet, with smooth mid vein and 2 indistinct lateral veins, surface shiny, with violet mid part and broad, yellow hyaline margin and apex. Lemmas 4–5 mm, lanceolate with lacerate apex, shiny, smooth and glabrous, with (3)5–7 indistinct veins, sometimes with a short awn 1–3 mm attached at the middle or upper part of the mid vein. Paleas strongly reduced or absent. No stamens observed.

The spikelet above the glumes is transformed into a leafy bulbil with several, green leaves.

Fruit

No fruits, but bulbils (vivipary).

Reproduction

Vegetative reproduction by bulbils; no seed production observed whatsoever, and probably no fragmentation of tussocks. Bulbil production abundant on Svalbard plants, and they sprout to 100 % (Alsos et al. 2013).

When bulbils are developed, they 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 ensuring a 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). We assume the viviparous Deschampsia alpina to be similar in this aspect.

In a largely unpublished study, L. Ryvarden showed that bulbils are very efficiently spread by wind over snow or even across mid-size ice-caps, and they kept their 'germination' ability even after very rough handling across glaciers (across the Hardangerjøkulen ice-cap in S Norway). The bulbils tested in his study were from Deschampsia alpina besides Festuca vivipara and two species of Poa. Bulbils do not depend much on favourable weather conditions for establishment; they usually develop whatever the conditions may be and very often 'germinate' on the plant after a winter under snow cover (R. Elven observ., Hardangerjøkulen area).

Comparison

The Svalbard grasses regularly reproducing by bulbils (vivipary) belong to three genera: Deschampsia, Festuca and Poa. Deschampsia alpina grows in tussocks like the viviparous species of Festuca but has much stouter leaves with marked veins on the upper surface (often hidden because the leaves have involute margins), shiny hyaline bracts (glumes and lemmas, whereas the two other genera do not have shiny bracts), and spikelets with only two functional flowers (sometimes an additional non-functioning flower). Both Festuca and Poa have several-flowered spikelets and firm (not shiny and hyaline) bracts. Viviparous Festuca and Poa are easily kept apart because the former has filiform leaves, the latter flat or folded leaves. There are also other good characters for recognition of Deschampsia (see its species).

The three species of Deschampsia in Svalbard are rather similar, being tussocky grasses with quite narrow leaves and large panicles with shiny bracts and only 2(3) flowers per spikelet. When bulbils develop, D. alpina is readily recognized from the two others. Before the bulbils develop, D. alpina resembles D. cespitosa. There are, however, three notable differences. Whereas D. alpina has almost smooth ribs on the upper leaf surface, smooth branches in the panicle, and usually involute leaves, D. cespitosa has strongly scabrous ribs, strongly scabrous branches in the panicle, and usually flat leaves. The character most clearly distinguishing young plants of D. alpina and D. cespitosa from those of D. sukatschewii is the number of veins in the leaves, 5–10 in D. alpina and D. cespitosa, 3–5 in D. sukatschewii which also has significantly narrower, filiform leaves.

Habitat

On moist, wet or irrigated, fine-grained substrates along rivers, brooks and lakes, on sediment plains, and in wet snowbeds. The species is indifferent as to soil reaction (pH), perhaps less common in regions with calcareous substrates.

Distribution

Common in all zones and sections. Common on all major islands in Svalbard and on several of the smaller ones: Bjørnøya, Prins Karls Forland, Hopen.

The global distribution is, as for many other viviparous grasses, concentrated to the regions surrounding the North Atlantic, from NE Canada across Greenland and Svalbard to Novaya Zemlya and south to the mountains in Scandinavia and the Murman area (Russia).

Comments

The viviparous Deschampsia alpina is similar and obviously closely related to the usually seminiferous D. cespitosa. There are viviparous biotypes of D. cespitosa, too, but these differ in having mostly flat leaves with scabrous ribs and also scabrous panicle branches. The chromosome numbers suggest some hybrid background; however, it is not likely that D. alpina has arisen from hybridization within D. cespitosa alone. Deschampsia s. str. (to which both D. alpina and D. cespitosa belong)has the rare basic chromosome number of × = 13. The diploid species with 2n = 26 are usually sexual and seminiferous, e.g., D. cespitosa, D. sukatschewii (in part),and the western arctic D. brevifolia R.Br. Deschampsia alpina is recorded with numbers 2n = 39–56, i.e., from triploid to ca. tetraploid, in Svalbard with 2n = ca. 39, 41, 49, and 50. If D. alpina has a hybrid background, D. cespitosa is an obvious candidate as one parent, and the other could be D. brevifolia. Its origin must, however, be far back in time. A major part of the present-day range of D. alpina is outside that of D. brevifolia, and in N Greenland, Svalbard, and Novaya Zemlya also outside that of native D. cespitosa. Today, there is no overlap between the native ranges of D. cespitosa and D. brevifolia (i.e., they are allopatric). For further discussion, see Elven et al. (2011).

Literature

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.

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