Seed Germination Ecophysiology of the Woodland Spring Geophyte Erythronium albidum

Abstract

Erythronium albidum is a spring ephemeral geophyte that grows in mesic deciduous forests of eastern North America. Flowering and seed production occur in early spring, and dormant seeds are dispersed in late May. Seeds sown on soil in a nonheated greenhouse in May germinated the following late winter and early spring when mean daily maximum and minimum temperatures were ca. 10-20 and 1-7 C, respectively. Embryos are underdeveloped and physiologically dormant when the seeds are dispersed. In seeds kept outdoors on moist soil under leaf litter, embryos grew from early September through late January, with most of the growth occurring in October and November. Although embryos require low temperatures for growth, they did not grow at 5 C unless previously given a warm stratification pretreatment at 30/15 C. Thus, warm followed by cold stratification is required to break seed dormancy. The lengths of these two stratification periods were quantified; at least 4 wk warm plus 8 wk cold stratification were necessary before seeds germinated to near 100%. In the woodland habitat, seeds are warm stratified during summer, and embryos grow when seeds are subjected to low temperatures during autumn and winter. Consequently, embryos are fully elongated by late January. Germination occurs as soon as temperatures become nonlimiting in late winter and early spring.