A Geographical Checklist of the Micronesian Dicotyledonae F. R. FOSBERG, MARIE-HELENE SACHET and ROYCE OLIVER Botany Department, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560 Abstract.-All species of dicotyledons known from Micronesia are listed along with their distribution by islands. Basionyms, synonyms and misapplied names that have been used for Micronesian plants are also listed. 1342 species and varieties are listed, 662 of them indigenous, 680 exotic. Of the indigenous ones, 78 are endemic to the Marianas, 267 endemic to the Carolines, 24 endemic to the two groups, the remainder are more widespread, 4 are named hybrids. The relationships of the flora are mostly Indo-Malesian and with the Melanesia-New Guinea area. The strand and coastal plants are mostly widespread, some of them pantropical.
Introduction
The islands of the Pacific basin termed by Dumont d'Urville "Micronesia" (the little lands) are, roughly, those groups lying north of the Equator, west of the International Date Line, south of the Tropic of Cancer, and east of the Philippines. In addition, the Gilbert group extends partly south of the Equator and the isolated raised atolls, Nauru and Banaba (Ocean), also lie south of the Equator. The archipelagoes in Micronesia are the Marianas, Carolines, Marshalls, and Gilberts. Included also are the more isolated islands, Marcus, Wake, Nauru, Banaba, and Mapia (Figure 1). This circumscription differs from that of Gressitt (1954) in that it excludes the Bonin and Volcano archipelagoes. The Gressitt volume cited is the best 路 geographic treatment available for Micronesia as a whole and was written to provide a biogeographical background for the series Insects of Micronesia edited by Dr. Gressitt, and published by the Bernice P. Bishop Museum. It includes a description pf the nature of the islands, which are mostly small, some of volcanic origin, some entirely made up of coral limestone arid a few of a more complex nature. Fosberg (1960) describes the vegetation of the archipelagoes, with special emphasis on the Marianas, particularly Guam. The present list of the vascular plant taxa of Micronesia is a summary of our floristic and geographic knowledge of the plant-life of the area. Our studies of the Micronesian flora started when the senior author helped sort the collection of Mr. M. Takamatsu on the Bishop Museum-Japanese Micronesian Expedition in 1936, and even earlier, when he identified an old collection of Guam plants made in 1900 by Wm. E. Safford and Alvin Seale and deposited in the B. P. Bishop Museum, Honolulu. Micronesica 15 (1 - 2): 41 - 295. 1979 (June).