226 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



small tree up to 4 m. (13 feet) high. The species was described from 

 California specimens. Trelease's treatment of the Arizona material 

 as distinct apparently was based on supposed differences in geo- 

 graphical distribution, but the species has a nearly continuous range 

 from California to New Mexico and, in the absence of morphological 

 difference, Q. subturbinella must be reduced to synonymy. By 

 reason of frequent misidentification, Q. turbinella in Arizona and New 

 Mexico has been much confused with Q. pungens Liebm. to which it 

 is not related and bears not even a superficial resemblance. The 

 species is rather close to Q. grisea Liebm. and occasionally is confused 

 with toothed-leaved forms of that species, but Q. turbinella is readily 

 recognized by its glaucous leaves. 



7. Quercus undulata Torr., Ann. Lye. N. Y. 2: 248. 1828. 



Quercus pauciloba Rydb., N. Y. Bot. Gard. Bui. 2: 215. 1901. 



Navajo, Coconino, Mohave, and Cochise Counties, commonly 

 6,000 to 7,000 feet. Colorado, Utah, New Mexico, and Arizona. 



Rocky Mountain shin oak. A low shrub, usually not more than 0.3 

 to 2 m. (1 to 6.5 feet) high, but attaining a height of 4 m. in moist, pro- 

 tected spots. It is a difficult species to understand and to characterize 

 adequately, because of its close relationship to forms of the series 

 Gambelieae, the multiplicity of its own leaf forms as well as those of 

 the closely related Q. pungens, and the total lack of constant ''key 

 characters." Its hard, persistent scabrous leaves link it definitely 

 with the more extreme Q. pungens from which it is distinguished by 

 the usually flat, shallowly toothed or lobed leaves. Some of the 

 Arizona specimens have been identified erroneously as Q. jendleri 

 Liebm. 



8. Quercus pungens Liebm., Overs. Danske Vidensk. Selsk. Forh. 



1854: 171. 1854. 



Swisshelm and Mule Mountains (Cochise County). Western 

 Texas to southeastern Arizona. 



A low shrub scarcely 2 m. (6.5 feet) high. The distinctive leaves, 

 pungently lobed and markedly crisped and scabrous, clearly dis- 

 tinguish this species from all others save occasional forms of Q. 

 vaseyana Buckl. of Texas. Q. pungens does not intergrade in Arizona 

 with Q. undulata, its closest relative in this State. 



9. Quercus subobtusifolia A. Camus, Soc. Bot. de Fr. Bui. 81: 816. 



1934. 



Quercus obtusifolia Rydb., N. Y. Bot. Gard. Bui. 2 : 213. 1901. 



Not Don. 

 Quercus undulata obtusifolia A. DC, Prodr. 16 2 : 23. 1864. 

 Quercus undulata Sarg., Silva 8: pi. 385, in part. 1895. Not 



Torr. 



In the mountains, probably of southern Arizona (Palmer in 1869, 

 Rothrock in 1874). Texas to Arizona. 



A shrub 1 to 3 m. (3 to 10 feet) high, growing usually on rocky slopes 

 at 7,000 to 8,000 feet. It is readily distinguished from Q. undulata by 

 its deciduous leaves with rounded, not mucronate lobes. From Q. 

 gambelii it may be separated by its obovate-cuneate leaves with 

 shallowly crenate margins, as contrasted with the deeply lobed 

 leaves of the other species. 



