Fig. 3.

Element concentrations in leaves and roots of the calcifuge Adiantum flabellulatum (Af) and the calcicole A. capillus-veneris f. dissectum (Ac) and A. malesianum (Am) grown on acidic, calcareous and mixed soils. Bar are means ± SE of 7 replicates from two-way ANOVA. Different letters indicate significant differences within the same tissue and element (P < 0.05). The dashed lines represent the average leaf element concentrations sufficient for adequate growth [16]. The solid lines represent the critical Fe toxicity concentration [17] or the threshold to distinguish Al-accumulators [18, 19]. The dotted line indicates the critical K deficiency concentration [20]