Fig. 2

Relationship between the leaf carbon isotope composition (δ¹³C) and the leaf thickness and the leaf mass per area (LMA) for the orchids and bromeliads listed in Table 1 and Additional file 1: Table S1. In (a) and (b) all orchids and bromeliads are plotted together, in (c) and (d) only orchids, and in (e) and (f) only bromeliads. Filled black symbols correspond to strong CAM species of orchids (▲) and bromeliads (●); symbols in grey correspond to weak CAM species of orchids () and bromeliads (); open symbols correspond to C₃ species of orchids (∆) and bromeliads (○). Values are means (n = 4). Regression coefficients between parameters were performed with R [55]