320 



The Oaks 



37. SHIN OAK Quercus undulata Torrey 



Qitercus grisea Liebmann 



This shrub occasionally becomes a small tree and is distributed from eastern 

 Colorado to western Texas, Nevada, New Mexico and Arizona, extending south- 

 ward into Mexico. It is also called Scrub oak and Switch oak. 



The bark is gray and flaky. The twigs are yellowish green and downy at 



first, becoming brown or gray. The buds are small, 

 blunt and brown. The leaves are oval to oblong or 

 oblong-lanceolate, 2 to 5 cm. long, blunt or pointed, 

 entire or wavy, or toothed on the revolute margin. 

 They are persistent, pale bluish green, hairy at first, 

 becoming smooth and shining above, paler and mostly 

 densely dull yellowish downy beneath; the leaf-stalk 

 is about 5 mm. long. The tree flowers in Texas in 

 April; the staminate catkins are hairy, 3 to 4 cm. long, 

 the calyx-lobes oblong, the anthers short-oblong, 

 smooth, on fihform Aliments. The fruit ripens in the 

 first season; nut oblong, about 1.5 cm. long, blunt or 

 sharp-pointed; cup saucer-shaped to hemispheric, 12 

 mm. across, embracing one fourth to one third of the 

 nut and covered by ovate corky thickened scales. 



Mohr's oak, Quercus Mohriana Buckley, usually 

 a shrub, of southwestern Texas and adjacent Mexico, 

 is sometimes arborescent and 4.5 meters tall. It dif- 

 fers from the above described species in its large, rela- 

 tively narrower leaves, which are light gray downy and not yellowish beneath. 

 The nut is relatively thicker and the cup more hemispheric. 



Quercus pungens Liebmann, is a shrub with crisped spiny-toothed leaves rang- 

 ing from Colorado and western Texas to Arizona, Cahfornia, and northern 

 Mexico. 



Quercus turhinella Greene, is a shrub ranging from New Mexico to Lower 

 California, with small acorns and small toothed or entire leaves, hairy beneath. 



Fig. 274. Shin Oak. 



38. BLUE OAK Quercus oblongifolia Torrey 



A native of western Texas, southern New Mexico, Arizona, and adjacent Mexico, 

 attaining a maximum height of about 9 meters, with a trunk diameter of 6 dm. 

 It is often called White oak. 



The branches are numerous, rather stout, spreading and ascending, often 

 forming a beautiful round-topped tree. The bark is up to 3 cm. thick, broken 

 into small close light gray scales. The twigs arc slender and stiff, slightly hairj^ 



