38 HOUGH'S AMERICAN WOODS. 



pale tomentose and with short, slender peduncles. Fruit acorns maturing the 

 first year, generally witii slender peduncles but sometimes sessile, a deep saucer- 

 shaped light brown cup with pale tomentose scales tuoerculate at base, about | 

 enveloping the oblong or ovoid nut which is 1 in. or less in length and about \ in. 

 broad, dark brown and longitudinally striated at first, but finally drying to a 

 light brown; cotyledons yellow. 



The specific name, Engelmanni, is given in compliment to the physician and 

 botanist, Dr. Geo. Engelmann. 



The Engelmaun Oak does not often attain a greater height than 50 

 or GO ft. (16 m.). Its trunk is rarely thicker than 2 or 3 ft. (0.75 m.), 

 and this divides quite regularly a few feet above the ground into two 

 large, widely diverging brandies which, by repeated bifurcation in this 

 way, form a rounded dome-shaped top. The bark of trunk is of a 

 light-gray color, fissured into longitudinal ridges, and exfoliating in 

 elongated friable scales. Its foliage is of a conspicuously bluish cast. 



HABITAT. A tree of very limited distribution, being confined 

 mainly to . the seaward slopes of the Sierra Madre and Santa Ana 

 mountains of southwestern California, easily distinguished from the 

 trees with which it grows by its bifurcate branching and the distinctly 

 bluish cast of its foliage. 



PHYSICAL PROPERTIES. Wood very heayy, hard, strong, and close- 

 grained, but rather brittle, with very dark-brown heart-wood and 

 lighter abundant sap-wood. Specific Gravity, 0.9441; Percentage of 

 Ash, 2.60; Relative Approximate fuel Value, 0.9195; Coefficient of 

 Elasticity, 85739; Modulus of Rupture, 719; Resistance to Longi- 

 tudinal Pressure, 434 ; Resistance to Indentation, 439 ; Weight of a 

 Cubic Foot in Pounds, 58.94. 



USES. This wood makes an excellent fuel, which is the only use 

 to which it is applied, owing to its limited distribution and abundance. 



216. QUERCUS MACDONALDI, GREENE. 

 MACDONALD OAK. 



Ger. , Eiche von Mac Donald; Fr. , Chene de MacDonald; Sp. , Roble 



de MacDonald. 



SPECIFIC CHARACTERS: Leaves deciduous, oblong to obovate.in outline, 1|- 

 3 in. long, sinuate-lobed, with-narrow and rounded or acute sinuses and broad 

 rounded or acutish and mucronulate lobes, wedge-shaped or rounded at base, finely 

 pubescent at first but finally glabrous above and stellate pubescent beneath: peti- 

 ole rather slender, pubescent. ^ in. or less in. length; branchlets slender, ferrugin- 

 ous pubescent the first year; winter buds in. or less in length, scales ciliolulate. 

 Flowers appear in April, the staminate in pubescent aments 1-2 in. in length; 

 calyx-lobes ciliate with pale silky hairs; pistillate flowers sessile or nearly so. 

 Fruit acorns maturing the first year, single or in pairs, sessile, with ovoid-oblong 

 nut, f to 1 in. long, acute or obtuse at apex, with a prominent terminal nib, nar- 

 row at base and about ^ enveloped in the deep hemispherical cup which is of a 



