One goal of Fairchild Tropical Botanic Garden’s conservation team is to increase the availability of plants that are native to our imperiled pine rockland habitat in South Florida. However, some species prove to be especially tricky to grow from seed and with the support of AZH we are now working towards unlocking the secret to their germination. Once we are successful, we will be able to grow these species in greater quantities, which will allow us to distribute them more widely through our outreach program the Connect to Protect Network as well as in habitat restoration projects in Miami-Dade and Monroe Counties.

The pine rockland is a fire dependent habitat and many species germinate abundantly after a fire, especially those growing in the herbaceous understory. Therefore, it is likely that at least some pine rockland species will produce seed whose germination is triggered by chemical signals from smoke.

Navy Wells Preserve in Miami-Dade County three months after a fire in 2013 (photo by Jennifer Possley)

By creating a smoke solution, we were able to bring the effect of fire into our seed lab. To catch all the water-soluble compounds of smoke we burned pine straw in a bee smoker and guided the smoke through a heater hose into a side-arm flask filled with water.

Setup to create a smoke solution that can be used to test the effect of fire on seed germination.

So far, we can report that using this smoke solution has improved germination in two species that were previously difficult to grow from seed. The most dramatic effect was in Blodgett’s silverbush (Argythamnia blodgettii) a federally listed species endemic to South Florida. But also, the germination of Pineland croton seeds (Croton linearis) improved significantly after the smoke solution treatment.

Germination of Blodgett’s silverbush seeds without treatment (left) and after soaking in smoke solution for 24h (right).

Besides testing how chemical signals from smoke can increase germination of pine rockland species we are now working to improve germination of additional species with different seed dormancy breaking methods, such as scarification, desiccation, and gibberellic acid.

We are very grateful for the support of this project from AZH!

Sabine Wintergerst, Seed Lab Manager, Fairchild Tropical Botanic Garden