From Mori et al. (in review)
Couratari clade (Prance, 1990b)—most species of this genus are very large, canopy or emergent, leptocaul trees with large buttresses found in lowland rain forests; the exceptions are those that occur in flooded forests (e.g., Couratari riparia, C.sandwithii and C. tenuifolia) and a few species from eastern Brazil, such as C. pyramidata that can occur in a shorter forest type called restinga in the vicinity of Rio de Janeiro. The flowers in this clade possess 6 petals, zygomorphic androecia (Figs. 7A, 7B, 7I), a staminal ring lip (Figs. 7I, 7J), and have fewer stamens (Fig. 7I) than the taxa in the other zygomorphic clades of neotropical Lecythidaceae. In species of Couratari, there are vestigial stamen nectaries the are also present in all species of Eschweilera; the ovaries are 3-locular (Fig. 7D), a feature also found consistently in species of Cariniana; some of the species possess stylar collars but that character also occurs in the Lecythis pisonis clade; the locules are vertically oriented and the ovules arise from placentae that cover the entire length of the lower septum; the fruits are very narrowly companulate (i.e., they taper toward the base, Fig. 7E) and not cylindric as they are in species Allantoma or broadly campanulate as they are in some species of Cariniana and Corythophora; the columella is tack-shaped (i.e., possesses a long, woody prolongation that extends into the fruit, Fig. 7F); and the cotyledons are leaf-like and opposite (Fig. 7H), which also occurs in species of  Cariniana and Couroupita. Two features are present in species of Couratari that are not present in any other clade of the family. One is an androecium that coils inward and then outward to form an external flap (Fig. 7B, 7K). Slight invaginations of the androecial hood also occur in species of other clades (e.g., Couroupita subsessilis, Eschweilera cyathiformis, and E. ovalifolia) but these taxa do not have a fully developed external flap. We hypothesize that the well-developed flap in Couratari protects the nectar from robbers such as trigonid bees. In support of this suggestion, we have observed that neotropical Lecythidaceae without external flaps often have their androecial hoods perforated by nectar robbers while the hoods of very few flowers of species of Couratari are perforated. The second defining character is seeds with a circumferential wing which we hypothesize to be derived from flattened seeds because the wings and seed have the same seed coat anatomy (see Fig. 13 in Tsou & Mori, 2002).