1. Department ofPUBLIC Health Sciences, University of Toronto, Toronto, Ontario, M5T 1R4; and Sporometrics Inc., 219 Dufferin St., Suite G20C, Toronto, Ontario, M6K 1Y9
2. Botany Department, Brandon University, Brandon, Manitoba, R7A 6A9
3. Department of Botany, University of Toronto, Toronto, Ontario, M5S 3B2