Castellanos C., Kolterman D. A. & Vester H. F. M. 2011. — Architectural analysis of Buxus vahlii Baill. (Buxaceae) in two different environments in Puerto Rico. Adansonia, sér. 3, 33 (1): 71–80.The analysis of the architecture of Buxus vahlii Baill. (Buxaceae) in western Puerto Rico is presented. Two populations growing in different environmental conditions were studied: one is a coastal forest in the municipality of Rincón and the other is a mountain forest with karstic formations in the municipality of Isabela. The growth pattern in Buxus vahlii follows Champagnat's model. Four stages of development were identified: seedling, juvenile tree, mature tree and senescent tree. The stem and branches of the tree are sympodially built by the superposition of mixed orthotropic axes. Two different crown shapes have been recorded in B. vahlii in Puerto Rico: in the Rincón forest, the shape is laminar, while in Isabela, it is in-between a funnel and cup shape.