In proportion to its area Ecuador is the floristically richest country in South America. About 230 families of vascular plants are known and the number of species has been estimated at something between 16,000 and 18,000. The richness of the flora is largely due to the diverse ecological conditions created by the great altitudinal differences. The land rises from sea level to nearly 6,300 m altitude. The vegetation varies from xerophytic scrub to rain forest and high-Andean pramos.
The present Flora Of Ecuador is the first ever published. It comprises all vascular plants, including commonly cultivated and escaped species, of the Ecuadorean mainland. It describes families, genera and species, and provides keys to genera and species. Remarks on nomenclature, intraspecific variation, Ecuadorean distribution and total range are included. Synonyms and collections studied are listed. Illustrations are provided for many taxa and descriptions of a large number of new taxa are published for the first time.
The Flora is published family by family (or in the largest families as parts thereof). The volumes are issued at irregular intervals as typescripts become ready for printing. The sequence and circumscription of the families follow, with minor deviations, Engler's Syllabus der Pflanzenfamilien, ed. 12. Up to May 1996, 78 families have been published, some families (Polypodiaceae, Compositae, Rubiaceae, Orchidaceae) only partially so. Treatments of many families are in preparation by specialists from different parts of the world, mainly Europe and the Americas.
The Riksmuseum, Stockholm (S), and the herbaria at the Universities of Göteborg (GB) and Aarhus, Denmark (AAU) are presumed to harbour about half of the Ecuadorean plant collections now existing. The present Flora is based on material in these as well as other important herbaria of the world.