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21. Quercus Arizonica Sargent, Gard. & Forest, 8: 92. 



1895. 



Qiiercus undulata Greene, W. Am. Oaks, 1 : 27, in part. 

 1889. 



Quercus Emory i Wats. PL Wheeler, 17. 1874. Not 

 Torr. 



Qiiercus undulata var. grisca Engelm. Wheeler's Rep. 6 : 

 250, in part. 1878. 



Quercus grisea Sarg. Forest Trees N. Am. joth Census 

 U. S. 9: 144, in part. 1884. Not Liebm. 



A tree occasionally 15-18 m. high. Bark of the stem 

 gray, usually cracked, fissured and scaly, that of the 

 branches gray or yellow, the young branches densely ful- 

 vous stellate; leaf-buds brown, pubescent: petioles 4-8 mm. 

 long, stellate : leaf-blades oblong or oblong-oval, acute, 

 obtuse or cordate at the base, firm, sinuate-dentate with 

 mucronate or spinulose teeth, 2—8 cm. long ; upper surface 

 nale bluish or yellowish green, not very shiny ; lower sur- 

 face stronglv reticulate, stellate-puberulent, pale yellowish : 

 fruit short-peduncled : cup hemispheric, 10-12 mm. in di- 

 ameter ; scales ovate, strongly corky-thickened on the back ; 

 acorn oblong-ellipsoid or elongated barrel-shaped, usually 

 2-2.5 cm - l° n g> obtuse, light yellowish brown. 



This species is very variable and seems to grade into Q. 

 reticulata on the one hand and Q. grisea on the other. 

 Two specimens cited below, collected in the Huachuca Moun- 

 tains bv Wilcox and Tourney seem to be intermediate be- 

 tween Q. Arizonica and Q. reticulata. The shape of the 

 leaves is that of the former but their size and obtuse apices 

 suggest the latter. Neither has any fruit, which would 

 otherwise help the determination, as Q. reticulata usually 

 has shorter and thinner cup-scales. 



It is still harder to distinguish this oak from Q. grisea. 

 As a rule the latter has also shorter acorns and less distinct 

 reticulation. Professor Sargent cites Quercus undulata var. 

 grisea Engelm. Wheeler's Rep. 6: 250 as a synonym of 

 Q. Arizonica ; this is only partly true, for one of Roth rock's 

 specimens in the U. S. National Herbarium is exactly like 

 Wright's no. 665 in the Torrey herbarium. The latter is the 



