Their flowers are unisexual, relatively small (around 1 cm long) and arranged in large panicles.

In 1944, Adolf Engler and Arthur Cronquist separated the species in the genus,[3] based mainly on the morphology of their flowers, but also using differences in their leaf structure.

[3][4] A phylogenetic analysis in 1995 based on the large sub-unit of rubisco suggested that Simarouba was most closely related to the Leitneria and Ailanthus genera,[5] but a later study in 2007, based on three chloroplastic genes and one nuclear gene,[6] found it was most closely related to Pierreodendron and Simaba.

The bark of Simarouba species has been used by indigenous tribes as a tea to treat many diseases.

[8][9] The seeds of Simarouba glauca have been proposed as suitable for producing edible oils in India.