Germination of Phacelia tanacetifolia seeds is inhibited by light. Embryos freed of endosperm grow irrespective of light. However, if they are held in 0.3 M mannitol plus 2% sucrose, light sensitivity is reinstated: growth (i. e., germination) occurs in darkness but not in light. Gibberellic acid
A role for inhibitors as regulators of seed dormancy in fire-dependent annuals and their nondormant (fire-independent) congeners was examined in the family Hydrophyllaceae. From seeds of the fire-dependent species, Emmenanthe penduliflora, Phacelia minor, P. brachyloba, and P. grandiflora, extracts