A Cladistic Analysis of the Plant Family Onagraceae

A cladistic analysis of Onagraceae was perforrned using 17 characters frorn rnor­ phology, anatorny, palynology, ernbryology, and cytology, with its 16 genera as the terminal taxa, and with several possible outgroups within Myrtales. In the rnain analysis (all Myrtales as outgroup ), seven equally parsirnonious cladograrns were produced, each with 29 steps and a consistency index of 0.82. A successive weighting procedure was applied, resulting in six cladograrns with a consistency index of 0.93. All cladograrns share the following nine rnonophyletic groups: 1) all taxa except Ludwigia; 2) Circaea (Fuchsia-Lopezia); 3) Fuchsia-Lopezia; 4) Gayophytum (Epilobium-Boisduvalia) (Gongylocarpus-Xylonagra-Camissonia(Clarkia(Hauya-Calylophus-Gaura)) (Oenothera-Stenosiphon)); 5) Epilobium-Boisduvalia; 6) Gongylocarpus-X y Ionagra-Camissonia( Clarkia(H auya-Calylophus­ Gaura ))(Oenothera-Stenosiphon ); 7) Clarkia(Hauya-Calylophus-Gaura); 8) Hauya-Calylophus-Gaura; and 9) Oenothera-Stenosiphon. One additional rnonophyletic group appears after applying the suc­ cessive weighting procedure: Gayophytum (Epilobium-Boisduvalia). Results of the cladistic analysis support a sister group relationship of Ludwigia to the rest of the genera. The clade of Circaea, Fuchsia, and Lopezia is the sister group of the rernaining genera (except Ludwigia), but there is relatively less resolution of the relationships arnong those genera (the tribes Onagreae, Epilobieae, and Hauyeae). The other rnain conclusions are that the positions of Hauya and Gayophytum are problernatic and not well resolved, and that the tribe Onagreae rnay be paraphyletic.