Foliar Anatomy of Three Native Species of Tillandsia L. from the Atacama Desert, Chile.

In the extreme north of Chile, the genus Tillandsia L. (Bromeliaceae) is represented by three native species, T. marconae Till & Vitek and T. landbeckii Phil., both of terrestrial atmospheric habit, and T. virescens Ruiz & Pav. of saxicolous habit. There is little information on the foliar structures that allow its establishment in arid environments. Therefore, we studied the leaf anatomy of each of these terrestrial and saxicolous atmospheric species from different altitudinal levels (1000 and 3000 m) in the Arica and Parinacota regions of the Atacama Desert. All populations are monospecific. The study considered scanning electron microscopy, optical microscopy, and the fingernail polish technique. The surface distribution of stomata and trichomes of the species is described. The studied species presented hypostomatic leaves, with anomocytic stomata and peltate trichomes on the abaxial and adaxial sides. Trichomes are formed by a central disc of four equal-sized empty cells, surrounded by a peripheral series of several concentric rings, the innermost of eight, the second of sixteen and the outermost of multiple elongated cells, one cell thick, that form the flexible asymmetric wings. The number of wing cells varies according to the species. Trichomes are evenly arranged in long lanceolate leaf blades with smooth margins.