XVI International Botanical Congess

Prosopis species (Algorroba, Mesquite) dominate the vegetation of arid regions of S W South America and S W North America. Our research shows that the Prosopis rusts Ravenelia arizonica and R. holwayi in North America and R. prosopidicola and R. chacoensis in South America are variants of one morphological taxon. These rusts incite spectacular perennial stem galls in which rust mycelium survives. Telial sori of R. holwayi form erumpent Asplash cups.@ Rain drops forcibly disseminate the large teliospores. Gelatinous contents of the spores= burst cyst cells stick to nearby leaves and stems where they germinate to produce basidiospores. Closely related species of Ravenelia and their legume hosts have a similar well known biogeographical distribution pattern.