Viviparous sheep's-fescue

Festuca vivipara, the viviparous sheep's-fescue, is a tufted perennial grass in the family Poaceae with a circumboreal arctic-alpine distribution across northern Europe, Iceland, the Faroes, Greenland, northern North America, and the higher British and Scandinavian mountains. The species is closely related to the common sheep's-fescue, Festuca ovina, and is sometimes treated as a viviparous variant of it. Plants form dense compact tufts of fine, wiry, almost bristle-like dark-green leaves 5-25 cm long, with a setaceous (hair-like) folded blade and a short membranous ligule. The flowering culms are erect, slender, 10-30 cm tall, and bear a contracted narrow panicle 2-6 cm long. The diagnostic feature of the species is its vivipary: the spikelets fail to set seed and instead proliferate into small leafy plantlets (bulbils) attached to the panicle, which eventually drop and root vegetatively. This pseudo-seed reproduction is an adaptation to short cool growing seasons in arctic and alpine habitats where ordinary sexual seed set is unreliable. The plant grows on rocky tundra, snow-bed margins, montane grassland, and damp acid mountain pastures.