Germination and Seed Bank Studies of Macbridea alba (Lamiaceae), a Federally Theatened Plant
Macbridea alba (Lamiaceae) is a Federally threatened plant endemic to Florida. Seedlings are rarely observed in natural populations, but seed production has been documented. We assessed the germinability of dry-stored seeds and of experimentally buried seeds, and sampled soil to detect a persistent seed bank.
More than 20% of recorded seeds germinated prior to collection, either within the calyx (viviparous seedlings) or after dispersal into the collection bag. This pre-collection germination indicated that a significant percentage of seeds lack innate dormancy. An estimated 87% of dry-stored seeds were germinable for six months following dispersal, but viability of dry-stored and of buried seeds was negligible after one year. No seedlings emerged from soil that was field collected just prior to seed dispersal, indicating no persistent seed bank. Seed viability does not appear to limit establishment, but dry conditions coincident with likely autumn establishment may limit seedling safe site availability.