THE SILVA OF COLORADO 



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Fig. 8. — Alder (Alnus tenuijolia). XJ. 



Genus 10. QUERCUS, Oak 



Eleven species of oak are recorded by Rydberg as occurring in Colo- 

 rado. They are found in the foothill districts at moderate altitudes, 

 chiefly in the southern and western parts of the state. The following 

 are the only trees. 



1 a. Leaves at maturity velvety beneath. 



lb. Leaves at maturity smooth or downy but never velvety beneath. 



2a. Mature leaves very thin. 



2b. Mature leaves firm. 



Quercus utahensis (DC.) Rydb. 

 "Utah Oak" 



(2) 



Quercus leptophylla Rydb. 

 "Colorado Oak" 



(3) 



