Leaf‐canopy‐induced Seed Dormancy in a Grassland Flora

SUMMARY The germination of 27 species from calcareous grassland was tested in three light treatments in the laboratory: in darkness, under tungsten lamps and under a leaf‐canopy. Germination was significantly lower under a leaf‐canopy than in the dark in 17 species. The phenomena of leaf‐canopy induced dormancy was not associated with the life‐span of species, though there was a weak, negative relationship with seed weight amongst 20 perennials in the sample. It is suggested that the co‐existence of species at high density in calcareous grasslands may, in part, be explained by differences in germination response to fine‐grained variations in the light environment at the soil surface.