Figure 1.

Presentation of the 2 species investigated in this study and overview of known CAM phenotypes and evolution in the subgenus Tillandsia. A)Tillandsia fasciculata, a “gray” or “atmospheric” Tillandsia with a dense layer of umbrella-shaped trichomes (inset), carbon isotope values within the CAM range, a lack of water-impounding tank, and roots adapted to the epiphytic lifestyle. The leaf close-up is at a 100 μm scale (also in B). Photograph by Clara Groot Crego. B)Tillandsia leiboldiana, a green Tillandsia with C3-like leaf morphology and carbon isotope values, an impounding tank, and a sparse trichome layer (inset). Photograph by Clara Groot Crego C) Schematic representation of the evolutionary relationship between the 2 investigated species of Tillandsia within the subgenus (modified from De La Harpe et al. 2020). Colors indicate reported carbon isotope values (Crayn et al. 2015; De La Harpe et al. 2020). The average was taken when multiple values have been reported for the same species. Pie charts at internal nodes show the ancestral state of photosynthetic metabolism as reported in De La Harpe et al. 2020. WHZ stands for Winter-Holtum Zone (Males 2018) and represents intermediate forms of the CAM continuum.