Summary
Quantitative morphological studies of the stomates of the stomates of thirty-seven species of Guttiferae were made. The species studied are members of the following genera: Caraipa, Clusia, Chysochlamys. Garcinia Haploclathra, Havetiopsis, Hypericum, Kielmeyera, Lorostemon, Moronobea, Oedematopus, Platonia, Quapoya, Rheedia, Symphonia, Tovomita and Vismia. Based on the relationshap between polar and equatorial diameters of the stomates, the 37 species can be grouped into five classes: I — Oblate-spheroidal; II — Prolate; III — Perprolate; IV — Prolate-spheroidal; and V — Subprplate. The epidermal cells of Caraipa excelsa, C. densiflora, Calophyllum brasiliense, Oedematopus obovatus, Platonia insignis, Tovomita mangle and Thysomostemon pakaraimae have sinous contour cell walls. In Rheedia, Quapoya, Clusia, Moronobea and Kielmeyera corymbosa, the guard cells have thick striations. In Chrysochlamys, Symphonia, Rheedia, and Kielmeyera corymbosa, the subsidiary cells have thick cuticles, generally with sinous striations. Using these data, a prelimnary key to genera and species was formed. In the future, the work will be extended to include other genera and species.