Germination Ecology of Collinsia verna, a Winter Annual of Rich Deciduous Woodlands

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Abstract
The germination ecology of C. verna Nutt., one of only a few native winter annuals that grows in rich deciduous woods in the eastern USA and adjacent Canada, was studied. Seeds are innately dormant at dispersal in late May and early June, but during summer they afterripen and become nondormant. During the afterripening periods, seeds gained the ability to germinate in light and darkness at 15.degree./6.degree., 20.degree./10.degree., 25.degree./15.degree. and 30.degree./15.degree. C. Seeds first germinated at 15.degree./6.degree. C (in July) and then at progressively higher tempertures. Germination at 30.degree./15.degree. C was delayed until Oct., at which time less than 25% of the seeds germinated. After germination began at a particular temperture regime, the germination percentage at that temperture increased as the seeds afterripened further, and by Oct. seeds germinated from 82-88% in light and darkness at 15.degree./6.degree. and 20.degree./10.degree. C. From July through Sept. habitat temperatures are too high for germination, and thus seeds do not germinate until early autumn when temperatures become non-limiting. Seeds planted on soil in a non-temperature-controlled greenhouse in early June 1978 and 1981 began to germinate in late Sept. and continued until early Nov. After the first autumn, no additional seeds germinated in either planting.