Biological Flora of the British Isles: Poa nemoralis

Abstract

1. This account presents information on all aspects of the biology of Poa nemoralis L. (Wood Meadow-grass) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation. 2. The grass Poa nemoralis is widespread and frequent to locally common across the British Isles, except for western and central Ireland, and northern Scotland. In both its native Eurasian range and introduced ranges in, for example, the Americas, its main habitat comprises temperate (mixed) deciduous woodland. The species finds important secondary habitats in hedgerows, as well as in non-woodland vegetation such as on cliffs, screes and walls or sporadically in grassland and heathland. Although not always taxonomically or morphologically distinct units, the species is suspected to comprise many cytological races and hybrid polyploid populations with variable morphology. Morphological variation among P. nemoralis populations may also be a sign of local environmental adaptation or a result of introgressive hybridization with other, morphologically variable members of Poa section Stenopoa such as P. glauca, P. compressa or P. pratensis. 3. Poa nemoralis is a small-statured, loosely caespitose grass, with populations ranging from a few individual tufts to those visually defining the aspect of the herbaceous understorey. The species tolerates moderate to deep shade on the forest