ensions of
cone and leaf and the number of leaves in the fascicle. These are so
accurately correlated with altitude and exposure, and are so
imperceptibly graded, that no specific segregations among them have
yet been successfully established.

The type-specimen figured by Lambert does not show the longest cone
and leaf of this species. They are better represented by specimens
which have been named P. filifolia. Such dimensions prevail in
subtropical localities. At temperate altitudes these dimensions are
much reduced, but here are found a longer form of cone and leaf (var.
Lindleyi, Loudon) and a shorter form (var. rudis, 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.

[Illustration: PLATE XXV. PINUS MONTEZUMAE]

39. PINUS PONDEROSA

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. macrophylla Engelmann in Wislizenus, Tour Mex. 103
(not Lindley).
1853 P. Jeffreyi 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. 202 (not Engelmann).
1859 P. deflexa Torrey in Emory's Rep. ii. 1, 209, t. 56.
1878 P. arizonica Engelmann in Wheeler's Rep.