XVI International Botanical Congess

Paulownia tomentosa (Scrophulariaceae) is a fast-growing tree native to China. Phenotypic plasticity is a potentially important trait for invasive species. We were interested in assessing the pattern of allocation in P. tomentosa along a light gradient over the course of a season. Plants were grown in a common garden in two replicate treatments of each: full shade, artificial edge (half of cage covered), and full sun (frame only). Two plants in each replicate were harvested in weeks 4, 7, 8, 9, and 11 after germination. Plants shifted allocation from below- to above-ground structures over time. The species showed a high level of phenotypic integration of biomass allocation that increased over the course of the experiment particularly in full sun. Our results are contrary to previous studies, perhaps because this is a long-lived heliophile.