2.4.2.2 Pasture grasses
In the other case involving pasture plants, namely forage grasses, a biotic driver of phenology has been long recognized, at least implicitly. A key phenological trait is the heading season, involving the seasonal timing and duration of seed-head development.
Late and brief heading and a semi-prostrate habit are features of persistent ‘pasture type’ cultivar strains, bred from material with an ancestral history of adaptation to intense grazing (e.g. Charles 1961). By contrast, ‘hay type’ strains do not have the same history of adaptation to grazing. They have earlier and longer heading seasons and a more erect habit, and much less sward persistence.