Figure 3. Provenance differences in leaf thermal tolerance of four tropical tree species grown under common environmental conditions. Panels show (a) values for Tcrit and (b) T50). Ca = Castanospermum australe, Hn =Homalanthus novo-guineensis, Me= Melicope elleryana, and Tm = Terminalia microcarpa . Data is of tree averages (n =6) presented as a box and whisker plots showing median and interquartile range, with the average marked by ×. Results of intraspecific t-test of provenance differences indicated by subscript ns=not significant, + is marginally significant at p < 0.1, * p < 0.05, ** p <0.001, and *** p < 0.0001.