For hundreds of years, plant taxonomists have worked to understand how species are related. Until relatively recently, their only reliable source of information about these relationships was the plants' morphologytraits that could be observed, measured, counted, categorized, and described visually. And paramount among these morphological traits were aspects of flower shape and arrangement.
In the papilionoid legumesa large, diverse group that includes the common pea and beanmost species have highly specialized, "butterfly-shaped" flowers with bilateral symmetry, fused stamens, and strongly differentiated standard, wing, and keel petals. Papilionoid genera with radially symmetric or weakly differentiated flower parts have been regarded as primitive members of the group. However, an international team of researchers have found that floral morphologies may be less reliable than other traits in determining the relationships of papilionoid species and genera. Their findings can be found in the recent issue of the American Journal of Botany.
Lead author Domingos Cardoso (Universidade Estadual de Feira de Santana in Bahia, Brazil) was intrigued by the floral diversity of papilionoid legumes. Growing up in the Caatinga regiona unique dry woodland biome in northeastern Brazil with many endemic legume speciesCardoso was fascinated by the beautiful mass flowering of leafless Luetzelburgia trees during the dry season. Despite their abundance in the Caatinga,Luetzelburgia species were poorly represented and often misidentified in herbaria. Furthermore, taxonomists had generally regarded Luetzelburgia and the putatively related Sweetia as primitive papilionoid groups because they lack the characteristic papilionate flowers. Yet, evidence from DNA sequences suggested that these plants were closely related to two rainforest genera with t
|Contact: Richard Hund|
American Journal of Botany