ECOLOGY OF THE ENDANGERED SPECIES SOLIDAGO-SHORTII .3. SEED-GERMINATION ECOLOGY

Seeds of Solidago shortii are conditionally dormant at maturity in October and November and thus require high temperatures (25/15, 30/15, 35/20-degrees-C) and light to germinate to 50% or more. Seeds stratified at 5-degrees-C for 12 weeks, as well as those that remained on plants in the field during winter became nondormant. During cold stratification, seeds gained the ability to germinate at low temperatures (15/6, 20/10-degrees-C) and lost the light requirement. Thus, in spring high percentages of the seeds can germinate over a wide range of thermoperiods (15/6-35/20-degrees-C) in both light and darkness. The seed dormancy/germination characteristics of S. shortii are similar to those of the geographically widespread species S. canadensis and S. nemoralis, and thus they do not help to explain the rarity of the species.