- Large trees.
- Leaves opposite, compound with 3 leaflets.
- Stipules absent.
- Flowers bilaterally symmetric with 5 free petals.
- Large, leathery fruit, with one or two large seeds.
Diagnosis: Trees, without stipules, large opposite leaves with 3 leaflets, entire and glabrous.
Local distribution: One species on high cloud forest ridges, the other on both slopes at about 700 to 1400 m.
|Bignoniaceae||: leaves opposite, but with more than three leaflets.
|Rutaceae||: a few species have opposite 3-foliolate leaves, but they are small trees with translucent yellow dots and aromatic odor.
Diversity: Total: 2 genera, 2 species. Trees: 1 genus, 2 species.
Comments: Both species can reach a large diameter. Billia is the only genus in Costa Rica.