Ontogenesis and variation of wood ‘parenchymatization’ in Cochlospermum vitifolium (Bixaceae)

Summary Axial parenchyma proliferation (non-lignified parenchyma) in wood has been characterized for only a few species. In the present study, we characterized the proliferation, ontogeny, and seasonal variation of wood axial parenchyma in Cochlospermum vitifolium (Bixaceae). This study included material from natural populations from different sites in Mexico. We analyzed the wood anatomy and development in stems of different ages, and monthly sampling of the main stem during the growing season. The results show that the wood anatomy of C. vitifolium is characterized by features associated with efficient water transport, such as wide vessels and low vessel frequency. The wood has a high storage and radial transport capacity. Axial parenchyma is abundant and constitutes the main cell type of the wood. Rays are wide and tall with a high starch content. Ontogenetic development of the wood showed that non-lignified axial parenchyma differentiates after secondary growth has been established. Parenchyma proliferation does not occur in an axially orderly fashion and the results suggest that there is a relationship between maximum proliferation and precipitation. We found high variation in wood parenchymatization between trees. The maximum parenchymatization and succulence was found in trees with larger stem diameter. The ecological and ontogenetic implications of wood parenchymatization are discussed.