XVI International Botanical Congess

Members of both tribes are recognized by their tree-like, shrubby or columnar stems, however scandent and globular forms occurred in Echinocereeae. The tribes in their present circumscription comprises 10 genera with 50 species in Pachycereeae and 5 genera with 100 species in Echinocereeae. The present comparative investigation concentrates on evaluating wood features to be incorporated in phylogenetic analysis. Wood of all genera was studied. With the exception of Echinocereus, genera have fibrous wood. Echinocereus possess wide band tracheids, unlignified rays and lack fibers, suggesting that other genera should be removed from the Echinocereeae. Genera with fibrous wood show few qualitative wood characters that distinguish them: rayless wood in Wilcoxia and mineral inclusion in Pachycereus. Quantitative characters were analyized by discriminant and multiple regression analyses. The analyses showed that fiber and vessel features were associated with latitude and habit. Results help to determine which characters and character states would be included in the cladistic analysis.