Cones deciduous at maturity. Cones ovate or ovate-conic. Conelet with tuberculate or entire scales. Resin-ducts external and medial 25. resinosa Resin-ducts septal and external 26. tropicalis Conelet with mucronate scales. Resin-ducts mostly external. Conelet pedunculate, erect. Cone nut-brown 27. Massoniana Cone dull tawny yellow 28. densiflora Conelet pedunculate, reflexed 29. sylvestris Conelet subsessile, erect 30. montana Resin-ducts mostly medial. Bark-formation late 31. luchuensis Bark-formation early. Cone nut-brown 32. Thunbergii Cone lustrous tawny yellow 33. nigra Cones narrow cylindrical 34. Merkusii Cones tenaciously persistent. Leaves stout, relatively short 35. sinensis Leaves slender, relatively long 36. insularis 25. PINUS RESINOSA 1789 P. resinosa Aiton, Hort. Kew. iii. 367. 1810 P. rubra Michaux f. Hist. Arbr. Am. i. 45, t. 1. Spring-shoots uninodal. Leaves binate, from 12 to 17 cm. long; resin-ducts external or external and medial; hypoderm uniform and inconspicuous. Scales of the conelet mutic. Cones from 4 to 6 cm. long, subsessile, symmetrical, deciduous the third year, leaving a few basal scales on the tree; apophyses sublustrous, nut-brown, somewhat thickened along a transverse keel. From Nova Scotia and Lake St. John this species ranges westward to the Winnipeg River and southward into Minnesota, Michigan, northern New York and eastern Massachusetts, with rare occurrence on the mountains of Pennsylvania. Under cultivation it is a beautiful tree, adapted to cold-temperate climates. It was considered by Loiseleur (1812) and by Spach (1842) to be a variety of P. nigra (laricio). The two species vary in the color of the cone, the anatomy of the leaves, the buds, and in the armature of the conelet. A fallen cone of this species is moreover usually imperfect from the loss of a few basal scales. Plate XIX. Fig. 170, Cone and enlarged conelet. Fig. 171, Leaf-fascicle and magnified leaf-section. 26. PINUS TROPICALIS 1851 P. tropicalis Morelet in Rev. Hort. Côte d'Or, i. 105. 1904 P. terthrocarpa Shaw in Gard. Chron. ser. 3, xxxv. 179, f. 74. Spring-shoots uninodal. Leaves binate, sometimes ternate, from 15 to 30 cm. long, rigid, erect; hypoderm of uniform thick-walled cells; resin-ducts of remarkable size, septal, or not quite touching the endoderm and technically external. Scales of the conelet minutely tuberculate. Cones from 5 to 8 cm. long, short-pedunculate, erect or patulous; ovate-conic, symmetrical; apophyses rufous brown, low-pyramidal, the umbo mutic.