C. San Martín

Morpho-ecological study on the South American species of the genus Nothofagus

The morphology of the 11 taxa of South American Nothofagus are compared. Thirty eight characteristics were taken into account: 12 from leaves, 3 from stipules, 3 from buds, 6 from cupules, 7 from fruits, 4 from petioles and 3 from male flowers. The data matrix, with average values of 100 measurements per taxon, was analyzed with multivariate statistical methods of classification and polar and spatial ordination. Five groups were established: The first one (Nothofagus obliqua, N. obliqua var. macrocarpa, N. leoni and N. alessandrii), with deciduous leaves, is adapted to mediterranean climatic conditions. The second groups (N. dombeyi, N. nitida and N. antarctica), with small leaves which are evergreen for the first two species and deciduous for the last, develops under temperate humid conditions typical of the Valdivian region. The three remaining groups correspond to isolated species with different requirements: N. glauca, has large deciduous leaves and colonizes the most xerophytic biotope that a Nothofagus in central Chile can tolerate. N. pumilio, with mid-sized deciduous leaves, is adapted to the cold and dry zones of the southern Andes. Finally, N. betuloides, with small evergreen leaves, grows in the cold/humid somewhat boggy conditions of the Magellanic region.