Effects of smoke on seed germination of twenty species of fire-prone habitats in Florida.
Seeds from 20 species of upland plants from Highlands and Polk Counties in south-central Florida, USA, were studied for smoke-responsive germination. The seeds were exposed to smoke for 0, 1, 5, 10 or 30 minutes. Germination trials were conducted on a covered veranda exposed to ambient light and temperatures. The majority of the seeds were incubated in Petri dishes, however, large seeds were planted in native yellow sand to minimize fungal attack. Among the 20 species tested, Liatris chapmanii, Polygala lewtonii and Abrus precatorius showed significant positive germination responses to smoke. The germination percentages for seeds of all 3 species were significantly higher than that of the control at 5 minutes of smoke exposure. The seeds of Liatris chapmanii and Abrus precatorius also showed increased germination when they were exposed to smoke for 1 minute. For seeds of Bejaria racemosa, Crotalaria pallida, Garberia heterophylla, Lechea deckertii, Liatris ohlingerae, Pityopsis graminifolia and Polygonella robusta, the germination percentages in the 10- and 30-minute trials were significantly lower than those in the control. For Bejaria racemosa and Lechea deckertii, there was no germination of seeds treated for more than 5 minutes. In Chamaecrista fasciculata, Dicerandra frutescens, Polygonella basiramia and Ziziphus celata, there was no significant difference in germination percentages among the control, 1-, 5- and 10-minute smoke treatments. Finally, no seeds of Callicarpa americana, Eryngium cuneifolium, Opuntia humifusa, Rhus copallinum, Serenoa repens or Sisyrinchium xerophyllum germinated.