8 GENUS PINUS 



THE CONE. Plate IV. 



The cone of Pinus shows great differences of color, form and tissue ; these are useful for specific 

 and sectional distinctions, while the gradual change from the primitive conditions of the Cembrae 

 to the elaborate form, structure and mode of dissemination of some serotinous species are obvious 

 evidence of an evolution among the species of remarkable taxonomic range. A form new among 

 Coniferae appears, the oblique cone, and a new condition, the serotinous cone, both appearing 

 at first alone and, finally, in constant association. 



COLOR OF THE CONE. 



With few exceptions the color of the ripe cone may be classified under one of the following shades 

 of brown or yellow. 



Nut-brown The stain of the walnut-husk. 



Rufous brown . .A pronounced reddish nut-brown. 

 Fulvous brown. .A yellowish nut-brown. 

 Tawny yellow . .The color of the lion. 

 Orange Ochre-yellow to red-orange. 



These colors may be paler or deeper. They may be obscured by a fuscous shade or may be modified 

 by a dull or lustrous surface. The presence of two or more of these shades in a single species and the 

 inherent difficulties of color description lessen the value of the character. Nevertheless certain 

 allied species, such as P. nigra and Thunbergii, or P. densiflora and Massoniana, may be distinguished 

 by the prevalent difference in the color of their cones. 



DIMENSIONS OF THE CONE. 



The cone is small, medium or large in different species, but varies greatly under the influences of 

 environment or of individual peculiarities. The character possesses relative value only, for great 

 variation is possible in the same locality and even on the same tree. 



THE PEDUNCLE. 



All conelets are pedunculate, but in some species the peduncle, even when long (patula), may 

 become overgrown and concealed by the basal scales of the ripe cone. Articulation usually takes 

 place between the peduncle and the branch, sometimes with the loss of a few basal scales which re- 

 main temporarily on the tree (ponderosa, palustris, etc.) . With P. Nelsonii, and to a less degree with 

 P. Armandi, there is articulation between the cone and its peduncle. 



There are several species bearing persistent cones with no articulation. This condition appears 

 in other genera, such as Larix and Picea, but without obvious significance. In Pinus, however, the 

 gradual appearance of the persistent cone, for it is rare, common, prevalent or invariable in differ- 

 ent species, and its essential association with the serotinous cone, suggest an evolution toward a 

 definite end. 



THE UMBO. 



The exposed part of the scale of the conelet is the umbo of the ripe cone, a small definite area 

 representing the earlier part of the biennial growth of the cone. The position of the umbo on the 

 apophysis is the basis of Koehne's subdivision of the section Haploxylon. 



1. Umbo terminal Subsection Cembra fig. 46-a. 



2. Umbo dorsal Subsection Paracembra fig. 46-b. 



Two other characters assist in establishing these subsections — the conelet, unarmed in Cembra, 

 armed in Paracembra — the pits of the ray -cells of the wood, large in Cembra, small in Paracembra. 



