About 1,500 collections from within 100 kilometers of the Arizona border in Sonora yielded noteworthy records for 164 plants including 44 new species (12 non-native) for Sonora and 12 (six non-native) for Mexico, conservation species, and regional endemics. Many common widespread species were poorly collected. Southern range extensions (120 species) were more numerous than northern extensions (20), although nine potentially occur in Arizona. Non-native species dispersed along highways and escaped from cultivation. The Turkish poppy (Glaucium corniculatum), established near Agua Prieta, may reach Arizona. African buffelgrass (Pennisetum ciliare) and Natal grass (Melinis repens) are rapidly expanding into new, higher elevation areas.