A population of Avicennia germinans (reproductive plant from 9 cm to 6 m height) growing along a salinity gradient (35 to 85 %) was studied at Salinas, Puntarenas, Pacific coast of Costa Rica. Trees from higher salinity areas were characterized by: smaller size, larger width to height ratio, smaller leaves, earlier and more profuse branching, allocation of a higher proportion of biomass to roots, and longer life expectancy of leaves.