The ecoregion is centered north and west of Lake Victoria, with an outlier on the border of Ethiopia and South Sudan.
It is bounded on the west by the higher-elevation Afromontane forests of the Albertine Rift, which separate it from the Congolian rainforests of the Congo Basin.
Characteristic trees include large-leaved albizia (Albizia grandibracteata), cheesewood (Alstonia boonei), false mvule (Antiaris toxicaria), African ita (Celtis adolfi-friderici), white stinkwood (Celtis africana), bastard white stinkwood (Celtis gomphophylla), red-fruited white stinkwood (Celtis mildbraedii), Celtis philippensis, Celtis zenkeri, white star apple (Gambeya albida), Uganda ironwood (Cynometra alexandri), Budongo mahogany (Entandrophragma angolense), Sapelli mahogany (Entandrophragma cylindricum), Budongo heavy mahogany (Entandrophragma utile), orange-barked terminalia (Holoptelea grandis), smooth-barked mahogany (Khaya anthotheca), big-leaf mahogany (Khaya grandifoliola), umbrella tree (Maesopsis eminii), Mildbraediodendron excelsum, mvule (Milicia excelsa), Uganda mulberry (Morus mesozygia), African greenheart (Piptadeniastrum africanum), aningeria (Aningeria altissima), and African nutmeg (Pycnanthus angolensis).
The reserve is secondary forest, and has been subject to long-term human influence, including logging since the early 20th century and encroachment by banana and coffee plantations in the 1970s and 80s.
The Kakamega and South Nandi forests in western Kenya occur 1520 to 1680 meters elevation, west of the highlands that bound the Eastern Rift.
Characteristic trees of the Kakamega and South Nandi forests include alangium (Alangium chinense), peacock flower (Albizia gummifera), pear wood (Apodytes dimidiata), bastard white stinkwood (Celtis gomphophylla), Gambeya gorungosana, drum tree (Cordia millenii), Ehretia cymosa, Budongo mahogany (Entandrophragma angolense), orange-milk tree (Harungana madagascariensis), river macaranga (Macaranga capensis), umbrella tree (Maesopsis eminii), calabash nutmeg (Monodora myristica), Neoboutonia macrocalyx, East African newtonia (Newtonia buchananii), aningeria (Pouteria altissima), red stinkwood (Prunus africana), jumping seed tree (Shirakiopsis elliptica), Strombosia scheffleri, Guinea waterberry (Syzygium guineense), Turraea holstii, and lemonwood (Xymalos monospora).
[7] A distinctive swamp forest community is found along the lower reaches of the Kagera River west of Lake Victoria, on the border of Tanzania and Uganda.