Pennington's monograph includes notes on taxonomic history, morphology and phylogeny, identification keys to the species in the various geographical regions where they occur, comprehensive descriptions of the individual species, an extensive list of exsiccatae examined and an index of vernacular names.
The genus Sloanea contains some of the most magnificent and spectacular rain forest trees in tropical America, reaching 40–50 m in height. They are conspicuous in having very large buttresses supporting the trunk, often more than 10 m high and spreading 3–4 m across the ground. The large buttresses, combined with the lack of coloured exudate in the cut bark, make identification to the genus easy, without recourse to leaves or flowers. Sloanea occurs in tropical America, Madagascar and tropical Asia where it extends as far as the Pacific. It is absent from continental Africa. In America it ranges from north west Mexico throughout Central America and the West Indies to the whole of tropical South America as far south as Bolivia, southern Brazil and Argentina.