Panarctic Flora


342601 Poa alpina L.


Geography: Amphi-Beringian - North American - amphi-Atlantic - European - Asian (NW-C).

Notes: Poa alpina is seminiferous throughout the major parts of its range but regularly viviparous populations are found in the North Atlantic regions, in some as predominant (the arctic Norwegian islands). The bulbil-reproducing var. vivipara does not differ from seed-reproducing P. alpina in other features and does not seem to have its origin in hybridization with other species. It is now treated as an ecotypical variety in Fennoscandia, Iceland, and Svalbard, or not accorded rank, whereas many authors outside northern Europe prefer rank as subspecies (Tzvelev PAF proposal and comments; Soreng et al. 2003; Soreng 2007). Both positions can be defended. The main argument for rank of variety or lower is that the switch between production of bulbils and seeds in P. alpina can be induced by temperature changes. The bulbil-reproducing plant is mostly confined to wet and/or cold sites along brooks, close to snowbanks, or in tundra. Iversen (1992) and Nordal and Iversen (1993) showed, in a local study in central Norway, that seed-reproducing and bulbil-reproducing plants often share isoenzyme multilocus phenotypes, i.e., assumed genotypes. The main argument for rank of subspecies is that the bulbil-reproducing plant has its own geographical range. It is narrowly amphi-Atlantic and arctic-alpine and does not reach west of eastern Greenland, whereas it totally predominates in the arctic Norwegian islands where only three populations of seed-reproducing plants are fully documented (O, TROM), whereas there is a nearly continuous population of viviparous plants in the islands. It is also common and locally predominant in the higher parts of the Scandes and in Iceland. The bulbil-reproducing plant shares its amphi-Atlantic pattern with several other viviparous grasses, and in these regions it reaches the Polar Desert zone at least in Svalbard. The seed-reproducing plant is nearly circumpolar but does not reach the northernmost zone(s). Variety vivipara is thereby a much more high-arctic (and high-alpine) plant than var. alpina, making the ranges of the two races rather different (parapatric).

Higher Taxa

  • Poa [3426,genus]