Smoke-Derived Cues for Seed Germination in the Post-Fire Recruiter Emmenanthe Penduliflora

Abstract

Wildfires are typically associated with the destruction of vegetation. However, in the chaparral of southern California, fires are responsible for the persistence of many species. In these communities, vegetative regrowth is accompanied by a striking post-bum recruitment of species from a flush of seed germination. Typically, the flora is dominated by “fire annuals” or those species in which occur primarily in the first year after fire and persist thereafter as deeply dormant seeds held in the seed bank until the next fire. Emmenanthe penduliflora (Hydrophyllaceae) is a prominent fire annual and possesses dormant seeds which germinate in response to smoke, extract of charred wood or nitrate-N. The underlying mechanism for these responses is unknown. Consequently, we initiated a systematic assessment of the ultrastructure of dormant (8% germination) versus smoke-treated seeds (79%) to identify changes which may be associated with the germination of E. penduliflora seeds.