Smoke-induced germination of succulents (Mesembryanthemaceae) from fire-prone and fire-free habitats in South Africa.

Previous studies have shown germination to be stimulated by fire-related cues such as heat and charate extract and, more recently, plant-derived smoke extract. However, smoke extract has not been tested on non-fire-prone species. We hypothesized that smoke-induced germination would be restricted to fire-prone species and investigated responses of members of the family Mesembryanthemaceae which has genera confined to fire-prone and to non-fire-prone habitats as well as genera with species across both habitats. Results of germination trials of smoke effects did not support the hypothesis. Plant-derived smoke extract stimulated germination in both fire-prone and non-fire-prone species. These results cast some doubt on the ecological significance of smoke as a fire-related cue and we suggest that investigation of effects of fire-related cues on non-fire prone species may throw light on general mechanisms of germination.