Abstract:
Herbarium- and field-based research indicates that the neotropical genus Swartzia is represented in Ecuador by at least 17 species. A key is provided to aid their identification. In addition, two species, previously undocumented in the literature, are described and illustrated. Both appear to be endemic to Ecuador. Swartzia decidua is known from a confined area of the pre-montane humid forest zone on the western slopes of the Andes Mountains in Pichincha Province, where it is threatened by habitat destruction. It belongs to S. sect. Paucistaminae and is notable in the context of the genus for its very large petal and deciduous phenology. Swartzia yasuniensis occurs in Amazonian rainforest in the drainage of the Napo River in Orellana Province and is a new member of S. sect. Pittierianae. In an intensively studied 25-hectare plot in Yasuni National Park, it averaged 4 individuals (≥1 cm dbh) per hectare.
