How Experimental Defoliation and Leaf Height Affect Growth and Reproduction in Trillium grandiflorum

ROONEY, THOMAS P. AND DONALD M. WALLER (Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison WI 53706). How experimental defoliation and leaf height affect growth and reproduction in Trillium grandiflorum. J. Torrey Bot. Soc. 128: 393-399. 2001.-Both defoliation and higher leaf placement can reduce growth in herbaceous plants. We examined variation in relative growth rate (RGR) and reproduction in response to defoliation and leaf height in Trillium grandiflorum at 4 sites in northern Wisconsin, USA. Plant biomass and the probability of flowering increased with increased leaf height. Analyses of covariance revealed that experimental defoliation and leaf height separately and independently reduced individual RGR, and accounted for about 42% of the total variance in RGR. Defoliation in 1998 had no effect on flowering in 1999, but leaf height in 1998 was positively associated with the likelihood of flowering in 1999. RGR and plant responses to defoliation varied among sites. We conclude that defoliation and leaf height reduce RGR over short time scales.