A Contribution to the Germination Ecology of Floerkea proserpinacoides (Limnanthaceae)

Abstract

Seeds of the spring ephemeral Floerkea proserpinacoides (Limnanthaceae) were dormant at maturity in mid to late May. Fresh seeds sown on soil in a non-temperature-controlled greenhouse in early June germinated from late December through mid February. Between December 22 and January 20, when mean daily maximum and minimum temperatures were 6.3 and 0.0 C, respectively, 78% of the seeds germinated. Fresh seeds were placed at 30/15 C (warm stratification) for 0-12 wk and then moved to 5 C (cold stratification). Seeds either remained at 5 C or after 0-12 wk were moved to 15/6 C. Cold but not warm stratification is required to break dormancy; however, warm stratification given prior to cold stratification decreased the length of the cold stratification period required to break dormancy. Seeds receiving no warm stratification reached 50% germination during the nineteenth week of cold stratification, whereas seeds given a 12-wk warm stratification pretreatment reached 50% germination during the eighth week after transfer to 5 C. The ability of nondormant seeds to germinate at low temperatures and the fact that warm stratification reduced the amount of cold stratification required for afterripening explain seed germination in winter.