CATALOGUE. 261 



so difficult as Pinus, but I find it impossible to unite it with any other of 

 the allied species. It has the cone of P. ponderosa, especially of that form 

 figured by Torrey as P. deflexa, and, like all forms of that species, it has 

 the peculiarity that the fallen cones, found on the ground, are always 

 imperfect, their lowest part remaining attached to the branch for another 

 season; I do not know of any other pine with this singular character. 

 But we could not well class this 5-leaved pine with the 3-leaved ponderosa. 

 On the other hand, the form of the cone and its scales will not permit us to 

 refer it to the Mexican P. Montemmce, though the structure of the leaf is 

 very similar to that of this polymorphous species, which appears to include 

 even P. Hartwegii. The three parenchymatous ducts of the leaf and the 

 strengthening cells* within the sheath of the vessels are exactly as we find 

 them in Montezumce, and different from ponderosa. 



Pinus ponderosa, Dougl. Parlat. 1. c. 305. — A large tree, with large and 

 spreading head, thick, deeply cracked, red-brown bark, and heavy, resinous, 

 yellowish wood ; thick branchlets, rough from leaf-scars and the persistent 

 remnants of bracts ; leaves in twos or mostly in threes, 4-8', in some rare 

 forms 10-1 2', long, § " wide, with sheaths at first 1' long, when old with- 

 ering to 2 or 3" long ; staminate flowers cylindric, with an involucre of 10 

 or 12 scales, the lowest pair of which is about two-thirds as long as the 

 innermost ; anthers with a large sub-orbicular crest ; fertile aments sub- 

 terminal ; patulous cones oval or rarely elongated, very variable in size, 

 2-6' long ; knob of the scales more or less prominent, and in some forms 

 even recurved, bearing a rather stout prickle ; seeds black, ridged on the 

 lower side, wing broadest in the middle ; cotyledons 6-8, or in the largest 

 seeds as many as 10. 



Colorado, New Mexico, and Arizona, extending through the Northern 

 Rocky Mountains and adjacent regions to Oregon and California, mostly in 

 the middle altitudes ; the most common and most useful timber of many 



"This namo has been given to longitudinal cells with very thick walls, destitute cf chlorophyll, 

 which are characteristic of most pine-leaves, and by their different disposition aid in distinguishing them 

 from one another. They are generally arranged close to the epidermis, and especially in the angles of 

 the leaves, and havo usually about tho same diameter as the epidermis-cells themselves. We find them 

 also occasionally surrounding the ducts, e. g. in P. ponderosa, also in the Cembroid Pines and in P. Bal- 

 fouriana and P. aristata; while in P. flexilis they always leave the ducts free, a character by which 

 wo can readily distingu'sh tho leaves of thtse species, otherwise so similar. Not rarely are they found 

 within the sheath, strengthening, as it seems, the ceulre of the leaf. 



