Fig. 235, Two cones of the species and the larger cone of the variety. Fig. 236, Leaf-fascicle and magnified sections of two leaves. Fig. 237 a, Dermal tissues of the leaf magnified; b, magnified cells of the leaf-endoderm. Fig. 238, Habit of the tree. 41. PINUS LAWSONII 1862 P. Lawsonii Roezl ex Gordon, Pinet. Suppl. 64. 1905 P. Altamirani Shaw in Sargent, Trees & Shrubs, i. 209, t. 99. Spring-shoots conspicuously pruinose, uninodal or not infrequently multinodal. Leaves in fascicles of 3, 4 or 5, not exceeding 24 cm. in length; resin-ducts internal, often with one or two medial ducts, hypoderm biform, endoderm usually with thin outer walls. Conelets mucronate. Cones from 5 to 7 cm. long on pliant peduncles, ovate or ovate-conic, oblique or sometimes symmetrical, deciduous, or persistent with a weak hold on the branch; apophyses nut-brown, flat or tumid, often protuberant on the posterior face of the cone, the umbo usually large and salient, forming a rounded button-like projection, on which the mucro is wanting. A subtropical species of central and western Mexico, growing alone or associated with P. oocarpa, P. Pringlei and the subtropical forms of P. Montezumae and P. pseudostrobus. It is recognized among its associate species by its conspicuously glaucous foliage. The cone is very variable on trees of the same grove, both in size and in the protuberance of its apophyses. Gordon's specimen in the Kew herbarium consists of a single detached cone and a few leaves. The leaves differ from all that I have examined in showing thick-walled endoderm cells, but the cone corresponds with many of my own collection. Plate XXVII. Fig. 239, Three cones. Fig. 240, Leaf-fascicle and magnified leaf-section. Fig. 241, Magnified cells of the leaf-endoderm. [Illustration: PLATE XXVII. P. TEOCOTE (235-238), LAWSONII (239-241)] 42. PINUS OCCIDENTALIS 1788 P. occidentalis Swartz, Nov. Gen. & Sp. Pl. 103. 1862 P. cubensis Grisebach in Mem. Am. Acad. ser. 2, viii. 530. 1880 P. Wrightii Engelmann in Trans. Acad. Sci. St. Louis, iv. 185. Spring-shoots uninodal, pruinose. Leaves in fascicles of 2 to 5, from 15 to 22 cm. long; resin-ducts internal, hypoderm biform, endoderm with thin outer walls. Conelets erect, aristate. Cones from 5 to 8 cm. long, reflexed, ovate, symmetrical, deciduous; apophyses nut-brown, lustrous, flat or tumid, the umbo often thin and, together with the slender prickle, bent sharply downward. This species is confined to San Domingo, Hayti and eastern Cuba. Its erect conelet and reflexed cone distinguish it from P. caribaea, which has both its conelet and cone reflexed. Moreover the conelet is usually, perhaps always, subterminal in P. occidentalis. Plate XXVIII. Fig. 247, Cone. Fig. 248, Conelet and enlarged aristate scales. Fig. 249, Magnified sections of two leaves and more magnified dermal tissues. 43. PINUS PALUSTRIS