TREES OF NORTH AMERICA 



Cone-scales armed with very stout hooked spines; cones 2^'-3' long; opening 

 in the autumn or remaining closed for two or three years; leaves 2' long or less. 



27. P. pungens. 



Leaves in 5-leaved clusters; cones 4/-6' long, unsymmetrical, their scales thick; seeds 

 longer than their wings; leaves stout, 9'-13' long. 28. P. Torreyana (G) 



9. Pinus leiophylla Schlecht. and Cham. Yellow Pine. 



Pinus chihuahuana, Erigelm. 



Leaves slender, pale glaucous green, marked by 6-8 rows of conspicuous stomata on 

 each of the 3 sides, 2|'-4' long, irregularly deciduous from their fourth season, their 

 sheaths deciduous. Flowers: male yellow; female yellow-green. Fruit ovoid, horizon- 

 tal or slightly declining, long- 

 stalked, l'-2' long, becoming 

 light chestnut-brown and lus- 

 trous, maturing at the end 

 of the third season, with scales 

 only slightly thickened, their 

 ultimately pale umbos armed 

 with recurved deciduous prickles; 

 seeds oval, rounded above and 

 pointed below, about ' long, 

 with a thin dark brown shell, 

 their wings f ' long and broadest 

 near the middle. 



A tree, rarely more than 40-50 

 high, with a tall trunk sometimes 

 2 in diameter, stout slightly as- 

 cending branches forming a nar- 



'2 row open pyramidal or round- 



topped head of thin pale foliage, 



and slender bright orange- brown branchlets, soon becoming dull red-brown. Bark of 

 old trunks f'-H' thick, dark reddish brown or sometimes nearly black, and deeply 

 divided into broad flat ridges covered w r ith thin closely appressed scales. Wood light, 

 soft, not strong but durable, light orange color, with thick much lighter colored sapwood. 

 Often forming coppice by the growth of shoots from the stump of cut trees. 



Distribution. Mountain ranges of southern New Mexico and Arizona, usually at eleva- 

 tions between 6000 and 7000; not common; more abundant on the Sierra Madre of north- 

 ern Mexico and on several of the short ranges of Chihuahua and Sonora, and of a larger size 

 in Mexico than in the United States. 



10. Pinus ponderosa Laws. Yellow Pine. Bull Pine. 



Leaves tufted at the ends of naked branches, in 2 or in 2 and 3-leaved clusters, stout, dark 

 yellow-green, marked by numerous rows of stomata on the 3 faces, 5 '-11' long, mostly 

 deciduous during their third season. Flowers: male yellow; female clustered or in pairs, 

 dark red. Fruit ellipsoidal, horizontal or slightly declining, nearly sessile or short-stalked, 

 S'-6' long, often clustered, bright green or purple when fully grown, becoming light reddish 

 brown, with narrow scales much thickened at the apex and armed with slender prickles, 

 mostly falling soon after opening and discharging their seeds, generally leaving the lower 

 scales attached to the peduncle; seeds ovoid, acute, compressed at the apex, full and rounded 

 below, I' long, with a thin dark purple often mottled shell, their wings usually broadest 

 below the middle, gradually narrowed at the oblique apex, !'-!' long, about 1' wide. 



A tree, sometimes 150-230 high, with a massive stem 5-8 in diameter, short thick 

 many-forked often pendulous branches generally turned upward at the ends and forming 



