Spring-shoots multinodal. Bark-formation late, the branches and upper trunk smooth. Leaves ternate, from 8 to 16 cm. long; resin-ducts medial or with one or more internal ducts, hypoderm biform. Scales of the conelet prolonged into a triangular spine. Cones from 8 to 16 cm. long, in verticillate clusters, sessile, reflexed, long-ovate, oblique, persistent and remarkably serotinous; apophyses lustrous tawny yellow, abruptly larger and more prominent on the posterior face of the cone, where they are usually prolonged into acute pyramids with a small incurved spine. A tree of slender habit and gray-green foliage, the trunk studded with persistent nodal cone-clusters; growing on dry mountain slopes, from southwestern Oregon over the foot-hills of the northern mountains of California and its coastal ranges as far as the southern slopes of the San Bernardino Mountains. It attains its best development in the northern part of its range, but is never a tree of importance. The serotinous habit is more pronounced in this than in any other species. It is distinct from P. radiata, its nearest relative, by the color of the cone, by its smooth upper trunk and by its much smaller size. The possibility of identifying P. californiana Loiseleur (Nouv. Duham. v. 293), through a cone said to have been sent to the Museum at Paris, may cause this name to be applied, by reason of its early date (1812), to some existing species. Don's radiata and tuberculata, although considered to be the same species, were nevertheless founded on different forms of the cone. Under a very narrow conception of specific limits tuberculata Don might therefore acquire specific rank. These considerations seem to make it advisable to abandon for this species the names californica Hartw. and tuberculata Gord. for the later name attenuata. Plate XXXVII. Fig. 317, Cone. Fig. 318, Magnified leaf-section. 63. PINUS RADIATA 1837 P. radiata D. Don in Trans. Linn. Soc. xvii. 442. 1837 P. tuberculata D. Don in Trans. Linn. Soc. xvii. 442. 1838 P. insignis Douglas ex Loudon, Arb. Brit. iv. 2265, f. 2171. 1841 P. Sinclairii Hooker & Arnott in Bot. Beechy Voy. 392, t. 93 (as to leaves). Spring-shoots multinodal. Bark formation early, the branches and upper trunk rough. Leaves ternate or binate, from 10 to 15 cm. long; resin-ducts medial or with an occasional internal duct, hypoderm biform. Conelets mucronate, the mucro small and dorsal. Cones from 7 to 14 cm. long, in verticillate clusters, sessile, reflexed, ovate or oblong, oblique, serotinous; apophyses nut-brown, lustrous, tumid in various degrees, the posterior scales abruptly larger and very prominent, the umbo bearing the minute prickle or its remnant.