XVI International Botanical Congess

Relationships within Atripliceae were examined by parsimony analysis of morphological variation in 70 cladistically informative characters. The study includes 68 terminals representing the 14 genera and all sections of the tribe, plus several outgroup genera. Thousands of specimens were examined in order to accommodate intraspecific variation. Homology hypotheses were postulated for features of gross morphology, anatomy, and pollen. Among the useful characters are previously unrecognized features such as crystals and stamen fusion. Nixon's parsimony ratchet was used to search for the most-parsimonious trees. Results suggest that neither Atriplex nor the tribe Atripliceae is monophyletic.