Abstract: Crown architecture of trees is the manner in which the foliage parts of trees are positioned in various microenvironments. Trees tend to attain a characteristic shape when grown alone in the open due to inherited developmental programme. This developmental programme usually implies the reiterative addition of a series of structurally equivalent subunits (branches, axes, shoots, leaves), which confer trees a modular nature. The developmental programme is the result of plant evolution under some general biomechanical constraints. The functional implications of the modular nature and the biomechanical constraints of shape, which in addition to the environment where the tree grows determine the tree crown architecture. Plant performance has a crucial link between its phenotype and its ecological success, and the crown architecture becomes ecologically and evolutionary relevant when it affects performance. Crown architecture is crucial for light capture and for the distribution of light to each particular photosynthetic unit of the crown. Tree crown architecture can be represented with ‘models’ which delineate the basic growth strategies that determine the successive architectural phases. More growth ‘models’ have been identified for the tropical trees than in the temperate trees. The forms and morphogenesis of trees are far more variable in the tropics than in the temperate regions.