Organization for flora neotropica

The following is a report on the formation of the "Organization for Flora Neotropica," its purpose, and the progress of its work. First, let me digress with some general observations. Few people will agree as to the precise geographic limitations of the New World tropical floras. An overly simple definition but sufficient for our purpose is those land areas lying between the Tropic of Cancer, 22?30'N, and the Tropic of Capricorn at 22?30'S. This will suffice to fix our attention geographically, and to lay some small background which would suggest that magnitude of the job ahead in the preparation of a floristic treatment for the vast area of more than 5,250,000 square miles (14,000,000 sq. km.). There have been a number of people who have been rash enough to make quantitative estimates of the flora of the Neotropics. Very early that courageous and astute collector, Richard Spruce, estimated the number of species of vascular plants of the Amazon Basin to be some 60,000. He wrote to George Bentham: "I have lately been calculating the number of species that yet remain to be discovered in the great A.mazon forest, from the cataracts of the Orinoco to the mountains of Matto Grosso; taking the fact that by moving away a degree of latitude or longitude I found about half the plants different as a basis, and considering what very narrow strips have, up to this day, been actually explored, and that often very inadequately, by Humboldt, Martius and myself, and others, there should still remain some 50,000 or even 80,000 species undiscovered." This was perhaps a near factual and prescient estimate. There remains today little better or more exact judgment than that expressed by Spruce more than a century ago. Some few markers may indicate the quality and extent of the New World tropical -floras. For the State of Rio Grande do Sul in southerln Brazil, Rambo, the author (with Lyman B. Smith) of the now nearly completed flora of that state, placed the number of species at 4,300, which he considers to comprise not more than 1/10 of the flora of Brazil. Therefore, from these figures we might estimate for Brazil a flora of some 43,000 species. The great Flora Brasiliensis of Martius, compiled over a period of 66 years and completed in 1906, accounted for only 22,766 species (2,253 genera), approximately half of the figures derived from Rambo. Steyermark (pers. comm.) has rated the species of vascular plants for Venezuela to be between 20,000 and 30,000 species. It has been estimated that the floristically richer Colombia contains from 30,000 to 40,000 species. Comparable figures would probably also apply to Peru. No estimates are available for Ecuador, Bolivia, Paraguay or the Guianas (except Suriname) in tropical South America. It seems not unreasonable, then, generously allowing for widespread distribution and overlap of species between national boundaries, that a minimum figure for the vascular flora of tropical South America may be put at some 80,000 species. This, together with a conservative estimate of 12,000 species for the Antilles and 20,000 species for Central America and tropical Mexico, adds up to 1-12,000; still a fantastic and staggering figure. The non-vascular flora may approach numerically that of the vascular plants. This would suggest the total number of plants, vascular and non-