| The Lake Nyasa Climatic Region described in this study is composed of the Livingstone, Kipengere, Mbeya, and Umalila ranges, Mporoto Ridge, Mt. Rungwe, and the Kitulo Plateau. The region is located on the rift escarpment at the northeast
end of Lake Nyasa. Floristic studies in the area reveal many unique plants, some of which are endemic to this region. The climate of the region is governed by altitude and its proximity to Lake Nyasa, which results in generation of high convectional rainfall. The high rainfall and diversity of habitats interacting with soils and other environmental factors in the area are responsible for the richness of the flora, and current identifications of vascular plant taxa have yielded a total of 170 families, 733 genera, and 1736 species. The Lake Nyasa Climatic Region, therefore, has nearly 14% of the estimated total of 12,500 vascular plant species in all of Tropical East Africa (H. Beentje, pers. comm.). The largest families in the flora are Fabaceae (s. str. excluding Caesalpiniaceae and Mimosaceae; 156 species in 42 genera), Asteraceae (139/55), Poaceae (124/50), Rubiaceae (119/49), and Orchidaceae (97/28); the largest genera are Crota-laria L. (Fabaceae, 30 species),Indigofera L. (Fabaceae, 22 species), Vernonia Schreb. (Asteraceae, 21 species), Cyperus L. (Cyperaceae, 21 species), Habenaria Willd. (Orchidaceae, 18 species), and Plectranthus L'Hér. (Lamiaceae, 18 species). Taxa here reported as new to East Africa are Cephalanthus natalensis Oliv. (Rubiaceae), Cerastium dregeanum Fenzl (Caryophyllaceae), Cynorkis symoensii Geerinck & Tournay (Orchidaceae), Dianthus zeyheri Sond. subsp. zeyheri (Caryophyllaceae), Panicum inaequilatum Stapf & С.E. Hubb. (Poaceae), Rhynchosia caribaea (Jacq.) DC. var. caribaea (Fabaceae), Tricalysia longituba De Wild. var. longituba (Rubiaceae), Tricalysia ngalaensis Robbr. (Rubiaceae), and Triumfetta angolensis Sprague & Hutch. (Tiliaceae); new to Tanzania from elsewhere in East Africa are Erica kingaensis Engl, subsp. bequaertii (De Wild.) R. Ross (Ericaceae), Peperomia fernandopoiana C. DC. var. butaguensis (De Wild.) Dull (Piperaceae), and Raphidiocystis jeffreyana A. Fern. & R. Fern. (Cucurbitaceae).
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