PINUS 171 



III. LEAVES IN THREES. 

 (a) Leaf-sheath deciduous. 



*Bun%eana. Leaf-sheath falling the first year. 

 Gerardiana. Leaf-sheath falling the second year. 



(b) Leaf-sheath rosette-like. 

 Cembroides. Leaves sometimes in pairs. 



(c) Leaf-sheath persistent ; buds resinous. 



*Coulteri. Buds conical ; leaf up to I ft. long. ^ 



Sabmiana. Buds cylindrical ; leaf up to I ft. long. | Young shoots orange-scented 

 *Ponderosa. Shoots brown ; leaf 5 to IO ins. long. f when cut. 



Jeffreyi. Shoots glaucous ; leaf 5 to 10 ins. long. J 



Rigida. Trunk furnished with small twigs. 

 *Radiata. Cones persisting long ; foliage grass green. 



Tuberculata. Cones persisting long ; leaf longer ; grey-green. 



IV. LEAVES IN FIVES. 

 (a) Leaf-sheaths persistent. 



Hartwegi. Leaves 5 to 6 ins. long. 

 Montezumce. Leaves 7 to 12 ins. long. 



(b) Leaf-sheaths rosette-like ; leaves not toothed. 



* Aristata. Leaves resin-dotted ; persisting twelve or fifteen years. 

 *Ba'fouriana. Leaves not resin-dotted ; persisting twelve to fifteen years. 

 Parryana. Leaves often in fours ; persisting two or three years. 



(c) Leaf-sheaths deciduous ; shoots downy. 



Armandii. Shoots sometimes glabrous like excelsa, but cones stouter (see figures). 



* A yacahuite. Basal scales of cone recurved. 

 Koraiensis, Bud-scales free at tips and spreading. 



* Cembra. Young shoots almost shaggy. 



* Lambertiana. Winter buds rounded or blunt. 



Strobus. Shoots downy only at base of leaf-bundle as a rule. 

 *. \fonticola. Shoots downy all over, otherwise similar to Strobus. 



Parviflora. Leaves I \ to 2\ ins. long, the shortest of this group. 



(d) Leaf-sheaths deciduous ; shoots glabrous. 



* Excelsa. Leaves 5 to 7 ins. long. 

 Peuke. Leaves 3 to 4 ins. long. 



(e) Leaf-sheaths deciduous ; leaf-margins not toothed. 



Albicaulis. Cones short and thick. 

 *Flexilis. Cones more slender. 



P. ALBICAULIS, Engelmann. WHITP: BARK PlNE. 



A shrub 10 to 20 ft high, rarely a tree twice as high ; in the smaller state 

 usually with two or three main stems. Young branchlets yellowish brown, 

 minutely downy or smooth, becoming grey the second or third year, finally 

 whitish. Leaves in fives, persisting five to seven years, i to 2\ ins. long, 

 green with whitish stoinatic lines on all three surfaces, stiffly pointed ; not 



