Senna (Cassiinae, Leguminosae) in Paraguay: synopsis, occurrence, ecological role and ethnobotany

MARAZZI, B., FORTUNATO, R.H., ENDRESS, P. K.& R. SPICHIGER

CANDOLLEA

Journal international de botanique systématique

Lugar: Ginebra; Año: 2006 p. 315 - 329

0373-2967

Senna (Cassiinae Leguminosae) is a large and diverse genus of about 350 species mainly distributed in the Tropics and in temperature America. We recognized 23 for Paraguay, one of them S. macranthera is new for Paraguay. Most species are widely distributed in Paraguay and are common ruderals of roadsides. However, four species, S. leiocarpa, S. rugosa, S. spiniflora and S. splendida, are know from less than three localities, and at least three other species are also rare.  The unclear conservation status to these species is especially due to habitat disruption by human activities, but also to the patterns of distribution of the species, to naturalization from cultivated plants, and perhaps to recent speciation. Senna species play an ecologic role by offering pollen to traplining bees and extrafloral nectar to ants. Although no Senna species is economically important  in Paraguay, some species were mentioned by ethnobotanists to be used by man, and others are cultivated as ornamental. The keys found in the most recent revision of the genus show systematic relationships between the Senna species, but are not a suitable identification tool. Thus, in addition to discuss the distribution, conservation status, ecologic role and aspects of etnobotany and ornamental plants, the present study includes a new practical determination key for the Senna species in Paraguay, with notes discussing potential identification problems.