Where There’s Fire There’s Smoke
Written by Johnny Randall, PhD, Associate Director for Natural Areas and Conservation Programs, North Carolina Botanical Garden, University of North Carolina at Chapel Hill
Many plants have seeds that respond to well-known germination cues such as the presence of water, exposure to red light, warm temperatures, scarification (such as the passing through an animal’s gut), and certain chemicals. All of these cues demonstrate some adaptation to the environment within which that particular plant occurs. And since plants cannot choose a preferred site for germination, these cues also help to ensure that a seed will tend to germinate in a place and time that might maximize its survivorship.
There is also a strong evolutionary relationship between a plant’s ecology and the mechanism, or mechanisms, that signal its seeds to germinate. My favorite example is how fire has shaped the general response of innumerable plant species across many different ecosystems. The most famous and well-studied of these is the Mediterranean-like ecosystems around the world such as southern California, South Africa, Western Australia, and (obviously) the Mediterranean region. Closer to home are the similarly shaped Piedmont and Coastal Plain Ecoregions that have a historical fire return of 4-6 years and 1-3 years, respectively. Fire ecology authority, Cecil Frost, reckons that 85% of the Piedmont flora, and over 90% of the Coastal Plain flora, is fire-dependent.
Plants adapted to fire also "know" that after a blaze many of their competitors will be reduced, nutrient-rich ash will be available, and that it’s time to germinate because of the clues from heat and the chemical signal from smoke – only recently identified as butenolide, 3-methyl-2H-furo[2,3-c]pyran-2-one. Smoke from burning plants itself is a well known germination stimulant and even store bought "Liquid Smoke" used in cooking does the trick! So the next time you’re smoking some salmon or brushing on some bottled smoke-derived seasoning, know that there are seeds that also enjoy those chemical stimulants and fiery flavors….