From the website:

Flora of North America builds upon the cumulative wealth of information acquired since botanical studies began in the United States and Canada more than two centuries ago. Recent research has been integrated with historical studies, so that the Flora of North America is a single-source synthesis of North American floristics. FNA has the full support of scientific botanical societies and is the botanical community’s vehicle for synthesizing and presenting this information.

Species descriptions are written and reviewed by experts from the systematic botanical community worldwide, based on original observations of living and herbarium specimens supplemented by a crucial review of the literature. Each treatment includes scientific and common names, taxonomic descriptions, identification keys, distribution maps, illustrations, summaries of habitat and geographic ranges, pertinent synonomy, chromosome numbers, phenology, ethnobotanical uses and toxicity, and other relevant biological information.

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