CSSA VOL.85, September-October 2013 No.5 CSSA tour 2012 - northwest Argentina its vegetation zones and the plants that live there Daniel L.Mahr The importance of habitat knowledge in the understanding of taxonomy in Cactaceae Guillermo Rivera Opuntia sulphurea in northwestern Argentina Judy Pigue Bromeliads of northwestern Argentina Nels Christianson Pterocactus of northwestern Argentina Root Gorelick A typical day on a CSSA fieldtrip Dick Schreiber Naturalist buddies and naked buds in northwestern Argentina Rick Gillman On the cover: One of the most photogenic and frequently photographed sites on the 2012 CSSA field trip was this landscape covered with Echinopsis atacamensis ssp. pasacana, along Salta provincial route 51 between Puerta Tastil and Santa Rosa de Tastil at an elevation of about 2766 m (9076 ft). Other plants growing there were Gymnocalycium spegazzinii, Paradia nivosa (faustiana form), Tunilla soehrensii and Cumulopuntia boliviana. The photographer, Nels Christianson noted that it was quite windy at the site.