Floral evolution in the legume tribe Amorpheae (eight genera, c. 240 species) has involved dramatic changes in the number, shapes, and positions of floral organs, including an unusual corolla-androecium synorganization. To study floral evolution in the tribe, we have reconstructed the phylogeny of the group, sampling heavily from genera for which we have morphological evidence that calls monophyly into question. Our preliminary results indicate that there are two major lineages, one consisting of three genera (Dalea, Marina, Psorothamnus) and the other of four (Parryella, Eysenhardtia, Errazurizia, Amorpha); the placement of monotypic Apoplanesia is uncertain. The first of these major clades includes floral diversity encompassing limited variation in the "papilionoid" floral form, but includes all cases of the corolla-androecium synorganization. The second clade includes a surprising level of diversity in petal number and floral symmetry. Psorothamnus is paraphyletic due to the placement of dalea-like P. emoryi as sister to Dalea plus Marina. Marina is supported as monophyletic, however Dalea is not. Dalea filiciformis shares many morphological characteristics with Marina and our results show that it is well supported as the sister group to Marina. The underused non-coding regions of the trnK intron (i.e., outside the coding region for matK) provided many variable and informative sites for resolving these relationships. Our well supported phylogeny of Amorpheae at the generic level provides a firm basis for refining classification of the tribe and analyzing processes generating floral diversity.

Key words: Amorpheae, Fabaceae, floral evolution, matK, phylogeny