Germination Response in Emmenanthe Penduliflora (Hydrophyllaceae)

Abstract

Emmananthe penduliflora Benth., postfire chaparral annual, has been shown in laboratory experiments to incorporate a unique mechanism allowing for the germination of its seeds. Only a few of the hundreds of E. penduliflora seeds tested would germinate following a period of incubation on either moist filter paper or soil. However, when burned stem segments of the chaparral dominant Adenostoma fasiculatum H & H. were placed on or immediately adjacent to E. penduliflora seeds, and incubated on moist soil at 10°C, germination occurred within 4 wk. Chaparral fires are generally believed to stimulate the development of a postburn flora through mechanisms involving sed coat scarification and/or the removal of allelopathic inhibitors to germination. The evidence presented herein suggests that for at least one postfire species the charred remains of chaparral vegetation serve as a germination trigger. Field experiments involving the effects of controlled burning and other manipulations of chaparral vegetation support the results. Relationships between these and other findings to the natural occurrence of Emmenanthe in California are discussed.