The western coast of South America [5-30°S lat] is dominated by desert conditions that form a continuous, hyper-arid belt, broken only by occasional river valleys. The native, non-riparian vegetation of these deserts is largely confined to localities where recurring fogs meet the near shore terrain. The fogs supply moisture for the development of unique plant communities termed lomas formations. Over 100 of these communities have been identified and they exist as terrestrial islands within the ocean of arid habitat ranging over 3500 kms from northern Peru to north-central Chile. Endemism reaches over 40% at some localities. The combined vascular flora of the lomas formations contains over 1400 species and the Solanaceae is represented by 19 genera and 129 species arrayed in five subfamilies: Cestroideae, Nicotianoideae, Petunioideae, Schizanthoideae, and Solanoideae. Lomas endemics are found in the following 11 genera: Exodeconus, Grabowskia, Leptoglossis, Lycopersicon, Lycium, Nolana, Nicotiana, Reyesia, Salpiglossis, Schizanthus and Solanum. Nolana, with 71 endemic lomas species, stands out as the largest and most wide-ranging genus of the lomas flora and the only one to be encountered in nearly all lomas formations. A suite of Nolana species have been investigated using ITS and matK sequence data to reconstruct phylogenies and these have yielded conflicting results. Morphological and physiological specializations that have allowed species diversification were examined in relation to suggested phylogenies. The biogeographic patterns within the Solanaceae lomas endemics reflect different arrival times and origins for its members. Short-term climatic fluctuations, such as El Niņo events, and longer-term climatic change associated with glacial cycles, are believed to have been influential in expansions and contractions in the flora of Andean Cordillera and the coastal deserts and have helped shape present-day distributional patterns.

Key words: Atacama Desert, biogeography, Lomas formations, Peruvian Desert, Solanaceae