Seed Germination of Hieracium pratense, a Successional Perennial

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Abstract
H. pratense (hawkweed) becomes established from seeds the 2nd spring after disturbance during old-field succession. Hawkweed is a perennial, and its seeds mature and are dispersed in June. Germination of buried and dry-stored seeds of hawkweed was investigated over a 1 yr period. Freshly harvested seeds showed some innate dormancy which was broken by a short period of afterripening. Germination of dry-stored seeds in light remained high throughout the testing period except at low temperatures (5-15.degree. C). Germination of seeds buried at 2, 5, and 15 cm was similar to that of the dry-stored seeds, but germination at low temperatures in light increased during the winter months. Laboratory stratification also resulted in increased germination at low temperatures. Germination of dry-stored and buried seed in the light was greater than in the dark. The burial experiments indicated short-term viability of hawkweed seeds in the soil. High-temperature drying had no harmful effect on germination, but solutions of high osmotic potential caused a decrease in germination. Increased far-red to red ratio of light passing through a vegetation canopy had little effect on germination. The ecological implications of these results are discussed.