Macroptilium (Benth.) Urban (Phaseoleae, Papilionoideae, Leguminosae) is an American genus of legumes, belonging to subtribe Phaseolinae along with other economically important genera, such as Vigna Savi and Phaseolus L. (the common bean genus). Cladistic analyses based on morphological, biochemical (storage seed proteins) and molecular (nuclear and plastid DNA sequences) data were performed on the 18 species currently ascribed to the genus, exploring several character weighting strategies. Equal weights, implied weighting and different transversion ⁄ transition costs were applied. The three data sets were first analyzed with separate partitions, and then combined into a single matrix. This study is the first one to analyze all the species of the genus from a cladistic point of view. In all the most parsimonious trees obtained, Macroptilium is monophyletic with excellent support values. Two monophyletic clades are recovered in almost all the analyses. Both are compound by nine species, and they constitute two sections of Macroptilium. Several interspecific relationships inside the genus are discussed.

A polymorphic population of Phaseolus vulgaris L. var. aborigineus (Burkart) Baudet growing in northwestern Argentina was studied. In order to know the origin of this polymorphism, plants belonging to the var. aborigineus, others showing floral dimorphism and individuals with weedy type characters were collected. Their seeds, obtained after fieldwork treatments of autogamy and free pollination in order to know their reproductive system, were sown in a greenhouse. Information of their growth was recorded and several numerical analyses were performed. With the results obtained, we concluded that those individuals that showed floral dimorphism are probably a result of hybridization and/or introgression between the var. aborigineus and cultivated forms that grow in the area. This hypothesis is supported by the presence of divergent segregation in the offspring. Also, the offspring of the F1 was followed and allowed us to conclude the possible existence of degeneration of the hybrid progeny. This degeneration indicates that an unwanted gene flow in the area could lead to a decline in the wild bean population. The vigour and high reproductive success of the offspring belonging to the individuals corresponding to the var. aborigineus, whose progenitor was treated for outcrossing, and the existence of plants with weedy type characteristics, are indicative of the necessity to preserve this germplasm in order to evaluate its agronomic potential as brief as possible. The population here studied constitutes a wild-weed-crop complex growing in Argentina.

The common bean (Phaseolus vulgaris L.) is a food of worldwide vital importance. Like any crop, the conservation of its wild relatives is essential to maintain the genetic variability needed for plant breeding. In situ conservation of such population has the additional benefit of generating new variations through the evolution of its natural environment. In 2004, wild populations of P. vulgaris var. aborigineus were found in the province of Co ´rdoba (Argentina), being the southernmost specimen of its current distribution. In order to study the state and characterize the environment of such populations, vegetation censuses were conducted along a stretch of the Tanti stream-arroyo Tanti-(Punilla, Co ´rdoba). Results showed that the wild bean has an intermediate to high constancy throughout the watercourse and its presence decreases upstream and away from the stream. Most cover took place in plots with scarce slope, high incidence of light and intense magnitude of floods. Vegetation develops in an environment surrounded by forests, meadows and intermediate physiognomy.Besides adventitious species, the studied area still has native species of high conservation value. Based on the analysis of this work, and considering the biogeographical significance of this population of wild bean, we conclude that this stretch of the studied stream is a priority area for the in situ conservation of P. vulgaris var. aborigineus.