A Physiological Study of Embryo Development in Heracleum sphondylium L: II. The Effect of Temperature on After-ripening

The action of low temperature in the after-ripening of seedsof Heracleum sphondylium is to make available the endospermreserves, without which the embryo is starved at room temperature.There is no development of 'secondary dormancy' in the embryo,since the effect of low temperature in after-ripening is strictlyadditive, and the total length of low-temperature treatmentrequired for germination is in no way influenced by periodsat room temperature before or during after-ripening.