Seedling growth protocol
Seeds of 53 diverse woody species, belonging to different growth-forms (19 trees, 22 shrubs, 6 subshrubs and 6 climbers or scramblers) and leaf habits (34 deciduous and 19 evergreens), were collected from cool-temperate and Mediterranean Europe (Table S1). These species are a subset of those used by Cornelissen et al. (1996), and the seedlings sampled for this anatomical study were subpopulations of those grown in that growth rate focused study, which was conducted in standard environmental conditions at the Unit of Comparative Plant Ecology, Sheffield University. In brief, throughout 1994 and 1995, all seeds were first germinated and then transplanted into experimental pots that were filled with quarried, prewashed silica sand. An environmental condition of 14 h 20-22 ℃ : 10 h 15-17 ℃ light : dark was provided, with 135 ± 10 µmol m-2s-1 of photosynthetically active radiation (classified as partial shade, see Hendry and Grime (1993)).
The population of each species was evenly divided into two halves for initial and final harvest. After the seedlings opened the first true leaf or leaf pair (i.e. at standardized ontogenetic stage), we harvested the first half population and determined the total plant dry weight. The second half of the population was cultivated for another 21 days within the same standard environment with 0.25 ml per sand volume full-strength Rorison nutrient solution (N, P and K at 56, 31 and 78 mg l-1, respectively, plus Ca, Mg, Fe and trace elements) and sufficient deionized water on alternate days. The seedlings were then harvested, dry-weighed and further treated for anatomy analysis (details see Cornelissen et al. (1996)).