Abstract: Studies of geographic distribution and physiological adaptations in the Bromeliaceae of coastal Chile and Peru provide insights into the ecological patterns of habit selection and speciation. The hyperarid coastal Atacama and Peruvian Deserts along the Pacific coast of South America contain a surprisingly rich flora of bromeliad species. These include representatives of all three Bromeliaceae subfamilies: two terrestrial Bromelioideae and two terrestrial Pitcairnioideae, all with rooted growth morphologies, and 14 species of Tillandsioideae (all Tillandsia L.) with epiphytic and unrooted, terrestrial representatives. The Bromelioideae are represented by two species of Puya MOLINA, one each in Peru and Chile. The Pitcairnioideae are represented by two genera, Deuterocohnia MEZ and Pitcairnia L'HÉRIT. with one species each. The 14 Tillandsia species are distributed in five subgenera which have successfully invaded the coastal deserts, and include both widespread and local endemics with xeromorphic adaptations. All the Tillandsia species are epiphytic in the broad sense, but in addition to growing on plants, they are found growing on rocks (i.e., saxicolous or epilithic). Six species (T. purpurea RUIZ & PAV., T. latifolia MEYEN, T. capillaris RUIZ & PAV., T. marconae TILL & VITEK, T. werdermanii HARMS, and T. landbeckii PHIL.) have evolved a highly specialized substrate ecology where they grow essentially unrooted on sand (i.e., epiarenic).
Nowhere in the world are bromeliads more dominant or have more biomass than in these coastal species growing on sand. Many of these species grow at the absolute limits of vascular plant tolerance, with the entire community consisting of a single Tillandsia species. Rooted, terrestrial bromeliads in the coastal lomas formations (all Pitcairnioideae) include CAM, C3, and C3-CAM flexible taxa in their metabolic systems, the CAM species growing in the most arid sites along the coast and C3 species growing in the most mesic habitats within the center of the coastal fog belt where fog moisture input is highest. All of the epiphytic Tillandsia species of the coastal desert region utilize CAM metabolism entirely or in part. At least two species, T. latifolia and T. tragophoba DILLON, utilize a flexible C3-CAM mode of carbon fixation. Whereas most of the desert-inhabiting Tillandsia species have relatively narrow leaves covered by water absorbing trichomes on their surface, T. multiflora BENTH. in northern Peru and T. tragophoba in northern Chile are tank-forming species where the bases of the leaves form a water-containing reservoir. The occurrence of the latter as a local endemic in hyperarid northern Chile is remarkable since it occurs thousands of kilometers south of its closest potential relatives in the central Andes.
The plates below correspond to the figures in the original publication.
[Page 270] Fig. 5. A-B (top) Tillandsia multiflora; A habit photograph at Cerro Campana, Peru, with scattered individuals of Puya ferruginea also present, B close-up of basal rosettes or "tanks" that retain water. C-D (bottom) Tillandsia tragophoba ; C habit photograph at Quebrada Rinconada, Chile, with the smaller, gray-leaved Tillandsia geissei growing sympatrically, D, close-up of a single individual.