Life span

Perennial, moderately long-lived.

Growth form

Solitary herb with a short, thick (starch-rich) rhizome often curved upwards at the apex. Stems single or several from rhizome apex, 3—10(15) cm, erect, glabrous. Leaves basal and cauline (lower part).

Leaf

Leaves alternate, (1)2—5(8) cm long, sharply divided into three parts: a sheath 15—40 mm, reaching well above the attachment point of the leaf petiole as an ochrea (a family character of Polygonaceae), pale brown with darker veins; a narrow, unwinged petiole 1—2.5(4) cm, inserted about half way up the ochrea or higher, about as long as the blade; and a blade 1—3.5 × 0.5—1.3 cm, ovate, oblong or elliptic, base truncate or rounded, rarely cuneate, apex subacute, mid vein raised on the lower surface, margins more or less revolute, upper surface dark green or reddish, glabrous, lower surface pale green with distinct lateral veins, glabrous or with very short (0.1—0.3 mm), articulate hairs.

Inflorescence

Inflorescence spike-like, narrow, 2—10 × 0.5—0.8 cm, with very short-stalked, 1—2-flowered cymes in the axils of 1.5—3 mm long, lanceolate, acute to acuminate, pale brown hyaline bracts with a dark brown mid vein. Inflorescence either with bulbils throughout or (more usual) with bulbils in the lower 1/3—2/3 of the ‘spike’ and flowers above.

Bulbils are pear-shaped (pyriform), 2—4 mm, red or blackish red. The bulbils often develop small, green leaves with a distinct petiole and a very short, ovate or obcordate blade, before being shed.

Flower

Flowers radially symmetric. Perianth with 5 subequal, free tepals, 2—4 mm, obovate, white or pink (often only one colour in each population). Stamens 8, often protruding from the perianth but also often aborting and not protruding. Gynoecium of 3 carpels with 3 styles.

Fruit

Fruit, when formed, a trigonous nut enclosed in the perianth, smooth and glossy.

Reproduction

Vegetative reproduction by bulbils. All reproduction in Svalbard is probably by bulbils. Occasional seed-set has been reported from other regions (Söyrinki 1989; Bauert 1993) but there are no reports of seeds partaking in any efficient reproduction in this species. The bulbils ‘germinate’ to 100 % in an experiment (Alsos et al. 2013). Bulbils of Bistorta vivipara are eagerly sought by birds and may be an important part of their diet, especially for chickens.

Dispersal of bulbils is likely to be by water (downstream, along the surface in strong downpours) and by mammals and birds as some of them may pass undamaged through the digestion system (if not chewed thoroughly enough).

Comparison

There is nothing similar to this species in Svalbard.

Habitat

Widespread in a broad range of site types from heaths to shallow mires and sediment plains, from dry to moist ground. The species is nearly ubiquitous in Svalbard vegetation types but rare in tall-grown vegetation where it is out-competed. Indifferent as to soil reaction (pH).

Distribution

This is one of the most common vascular plant species in Svalbard, distributed in all zones and sections and on all the larger islands (Bjørnøya, Spitsbergen, Edgeøya, Barentsøya, Nordaustlandet, and Prins Karls Forland).

The global range is circumpolar in the arctic and boreal zones, very common in all northern areas.

Comments

Bistorta vivipara is reported with high and irregular chromosome numbers of ca. 77—ca. 132, whereas its relatives in the regularly seed-reproducing B. officinalis complex have 2n = ca. 44—ca. 50 and 72 (Elven et al. 2011). We suspect that the switch from production of seeds to bulbils have a connection with the high and irregular chromosome numbers. There are several investigations of the genetics of B. vivipara showing that, in spite of the overwhelmingly asexual reproduction, there is a high level of genetic variation, especially in arctic and alpine populations (Bauert 1996; Diggle et al. 1998) and also a significant polymorphy, often within populations (Dormann et al. 2002, on Svalbard populations), but without obvious adaptive reactions. This is just a very successful species reproducing vegetatively throughout its range. As to the origin of the species, Marr et al. (2013) found genetic support for an Asian origin and an early spread (at least before the last major glaciation) to North America and Europe.

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.

Bauert, M.R. 1993. Vivipary in Polygonum viviparum: an adaptation to cold climate? – Nordic Journal of Botany 13: 473-480. Doi 10.1111/j.1756-1051.1993.tb00085.x.

Bauert, M.R. 1996. Genetic diversity and ecotypic differentiation in arctic and alpine populations of Polygonum viviparum. – Arctic and Alpine Research 28: 190–195. Doi

Diggle, P.K., Lover, S. & Ranker, T.A. 1998. Clonal diversity of alpine populations of Polygonum viviparum (Polygonaceae). – International Journal of Plant Science 159: 606–615. Doi

Dormann, C.F., Albon, S.D. & Woodin, S.J. 2002. No evidence for adaptation of two Polygonum viviparum morphotypes of different bulbil characteristics to length of growing season: abundance, biomass and germination. – Polar Biology 25: 884–890. Doi

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

Marr, K.L., Allen, G.A., Hebda, R.J. & McCormick, L.J. 2013. Phylogeographical patterns in the widespread arctic–alpine plant Bistorta vivipara (Polygonaceae) with emphasis on western North America. – Journal of Biogeography 40: 847–856. Doi 10.1111/jbi.12042.

Söyrinki, N. 1989. Fruit production and seedlings in Polygonum viviparum. – Memoranda Societatis Fauna Flora Fennica 65: 13–15.