The evolutionary relationships among the seven tribes of Onagraceae, the most intensively studied family of intermediate size, have been examined from morphological and molecular perspectives. Previous cladistic analyses of chloroplast (cp) and nuclear ribosomal (nr) DNA restriction sites, nuclear-encoded rbcS amino acid sequences, nrRNA nucleotide sequences, and morphological characters, produced trees that agree in defining the tribe Jussiaeeae as the sister group to the rest of the family. However, the relationships among the rest of the tribes are not completely resolved by these analyses. Cladistic analyses of sequence data from the chloroplast encoded rbcL gene produced results that bear on two malor issues: (i) intertribal relationships within Onagraceae, and (ii) congruence with other cladistic analyses