  
        Pine-oak forest on Mesa del Campanero near Yécora, Sonora. Photo: Mark Dimmitt  | 
        
          Pine-oak forest at El Aguajito on Mex 16 west of Yécora, Sonora. Photo: T.R. Van Devender        | 
    
    
        
        Pine-oak forest at El Aguajito on Mex 16 west of Yécora, Sonora. The white-flowered shrubs in the understory are Montanoa leucantha; the yellow ones are Xanthocephalum eradiatum. Photo: Mark Dimmitt  | 
        
        Pine-oak forest near Maycoba, Sonora. Photo: T.R. Van Devender  | 
    
    
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      | In the above two images taken in March the oaks are readily discerned by their colorful foliage. Madrean "evergreen" oaks shed their leaves in spring; they usually releaf a couple of weeks later, or in dry seasons wait until the summer rains. Left: east of Yécora, Sonora; photo T.R. Van Devender. Right: east of Hermosillo, Sonora; photo Mark Dimmitt | 
      
    
        
        Mexico Hwy 16 runs from desert in Hermosillo, Sonora to pine forest in Chihuahua. This is pine-oak forest near Yécora. Photo: T.R. Van Devender  | 
        
        Forest with Pinus durangensis and Quercus albocincta (shedding their leaves) at Agua Amarilla, Sonora. Photo: T.R. Van Devender | 
    
    
        
        View from edge of Mesa del Campanero near Yécora, Sonora. Photo: T.R. Van Devender  | 
        
        Meadows within pine-oak forest support colorful wildflowers in summer. Mesa del Campanero near Yécora, Sonora. Photo: T.R. Van Devender  | 
    
    
        
        Mesa del Campanero near Yécora, Sonora. Photo: Mark Dimmitt  | 
        
        Rancho Santa Bárbara northeast of Alamos, Sonora. Pinus oocarpa in foreground. Photo: George M. Ferguson |