ee GENUS pmus 



Shaw). At still higher altitudes and up to the timber-limit the var. Hartwegii, Engelmann, with 

 short leaves and a small nearly black cone is found. Among these varieties there is no such sharp 

 distinction as these definitions imply. All dimensions of fruit and foliage and the various brown and 

 black shades of the cone blend into each other through endless intergradations. A monograph of this 

 species, by one who could devote some years to it on the superb volcanoes and in the delightful 

 climates where this tree abounds, would be a valuable contribution to science. 



Plate XXV. (Cones and leaves much reduced.) 



Fig. 220, Cone and leaves of Lambert's plate. Figs. 221, 222, Longer cones and leaves of 

 the species. Fig. 223, Cone and leaves of var. Lindleyi. Fig. 224, Cones and leaves of var. 

 rudis. Fig. 225, Cone and leaves of var. Hartwegii. Fig. 226, Magnified leaf-sections. Figs. 

 227, 228, Two forms of the dermal tissues of the leaf, magnified. Fig. 229, Habit of the tree. 



PINUS PONDEROSA i 



1836 P. PONDEROSA Douglas ex Lawson's Agric. Man. 354. 



1847 P. Benthamiana Hartweg in Jour. Hort. Soc. Lond. ii. 189. 



1848 P. BRACHYPTERA Engelmann in Wislizenus, Tour Mex. 89. 



1848 P. MACROPHTLLA Engelmann in Wislizenus, Tour Mex. 103 (not Lindley) . 



1853 P. Jeffrey: Balfour in Bot. Exp. Oregon, 2, f. 



1854 P. Engelmanni Carriere in Rev. Hort. 227. 



1855 P. Beardsleyi Murray in Edinb. Phil. Jour. ser. 2, i. 286, t. 6. 

 1855 P. Craigana Murray in Edinb. Phil. Jour. ser. 2, i. 288, t. 7. 



1858 P. Parryana Gordon, Pinet. 2d2 (not Engelmann). 



1859 P. DEFLEXA Torrey in Emory's Rep. ii-1, 209, t. 56. 

 1878 P. ARizoNiCA Engelmann in Wheeler's Rep. vi. 260. 

 1889 P. LATiFOLiA Sargent in Gar. & For. ii. 496, f. 135. 

 1894 P. APACHECA Lemmon in Erythea, ii. 103, t. 3. 



1897 P. Mayriana Sudworth in Bull. 14, U. S. Dept. Agric. 21. 

 1897 P. scopuLORUM Lemmon in Gar. & For. x. 183. 

 1900 P. PENiNSULARis Lemmon, W. Am. Conebear. 114. 



Spring-shoots uninodal, sometimes pruinose. Bark-formation early. Leaves prevalently in fas- 

 cicles of 3, but varying from 2 to 5 or more, from 12 to 36 cm. long; resin-ducts medial, hypoderm 

 uniform or multiform, outer walls of the endoderm thick. Conelet mucronate, the mucro often 

 reflexed. Cones from 8 to 20 cm. long, ovate-conic, symmetrical, deciduous and usually leaving a 

 few basal scales on the tree; apophyses tawny yellow to fuscous brown, lustrous, elevated along 

 a transverse keel, sometimes protuberant and reflexed, the umbo salient and forming the base 

 of a pungent, persistent prickle. 



This species ranges from southern British Columbia over the mountains between the Pacific and 

 the eastern foot-hills of the Rocky Mountains, including the Black Hills of South Dakota, to the 

 northeastern Sierras of Mexico, to northern Jalisco and Lower California, forming, in many locali- 

 ties, large forests and furnishing the best Hard Pine timber of the western United States. It attains 

 its best growth on the Sierras of California and is, next to P. Lambertiana, the tallest of the Pines. 



Like P. Montezumae, and under like influences, it shows much dimensional variation, and the 

 leaf-fascicles are heteromerous, with the larger number in the southern part of its range. Many 

 authors consider the variety Jeffreyi Vasey to be a distinct species; but here, it seems to me, too 

 much importance is attached to the pruinose branchlet, clearly a provision against transpiration 

 and associated rather with a dry environment than with a species. Most observers discover many 

 intermediate forms between this variety and the species. The var. scopulorum Engelm. is the Rocky 

 Mountain form with leaves in 2's and 3's and with small cones passing into P. arizonica, Engelm., 

 a more southern form with small cones and leaves in fascicles of 3 to 5. The var. macrophylla 

 (Shaw, Pines Mex. 24), in addition to its long and stout leaves, bears a cone with protuberant 

 apophyses, somewhat comparable to the intermediate forms of P. pseudostrobus var. apulcensis 



