All vines shrubs and trees with d.b.h. ‚â•2.5 cm were recorded within 30 transects in 2 upland areas and in the arroyo (stream) floodplains at Chamela Jalisco Mexico. Av. rainfall is 748 mm with a 4-month wet season. Transects totalling 0.3 ha included 176 species and 1352 woody plants. Upland and arroyo sites were similar in species number but the latter included significantly more vines and large trees. Overall flora was quite distinct between the upland and arroyo habitats. Of the 26 species sampled in 2 of the 3 sets 54% were sampled only in the upland sets while 47% of all species in the arroyos did not occur in any upland transect. Mean b.a. on the arroyos was more than twice that on upland areas.