170 TRANS. ST. LOUIS ACAD. SCIENCE. 



The carpellary scales, which in the flower as well as in the 

 fruit we call, in short, scales, are either rounded, obtuse, and 

 appressed (in Strobus, etc.), or they have a short {P. resinosa^ 

 sylvestris, etc.) or a longer {P. ponderosa, Tceda) or an elon- 

 gated, subulate, often squarrose, point {P. contorta, inops, 

 pungens^. 



The aments are globose, oval or elongated, subsessile or pedun- 

 cled, single or several together, always erect, each borne in the 

 axil of a bract, its base invested by sterile bracts which gradually 

 or suddenly give place to the carpel-bearing bracts, just as the 

 involucral scales of the male flowers give place to stamens. They 

 make their appearance on the upper part of the year's shoot, 

 often just below the terminal bud, when we call them siibter- 

 ?ninal ; or they become lateral, when the axis elongates beyond 

 them, and sometimes more aments form above them in the same 

 season. The axis above the aments continues covered with leaf- 

 bundles in some, while in others it is naked for some distance, or 

 rather destitute of leaves, bearing only bracts ; a second stage 

 of aments or the terminal bud is always preceded by a number 

 of leaf-bundles. 



The position of the female ament, whether subterminal or late- 

 ral, seems to be connected with an essential difference in the spe- 

 cies of pines, secondary in importance only to the leaf structure as 

 described above, and both of these together will enable us to ar- 

 range the species in something like a natural order. It ought to be 

 understood, however, that the relative position of the ament on the 

 axis is not absolute and that variations do occur. Species with or- 

 dinarily subterminal aments mav in young and vigorous shoots 

 sometimes bear lateral aments ; this occurs, though very rarely, 

 in P. po?iderosa- and australis, and perhaps in others, but I have 

 never seen it in any of the Strobus section, nor in P. sylvestris, 

 resinosa, Laricio or its allies. More frequently subterminal 

 aments are found in species which normally bear lateral ones, 

 probably when with the formation of the aments the vigor of the 

 axial growth has been exhausted ; thus sometimes a second stage 

 of aments is subterminal, while the first is of course lateral ; or 

 subterminal and lateral ones are occasionally found on differ- 

 ent branches of the same tree ; or, very rarely, a tree bears al- 

 most entirely subterminal aments. This last case I have seen in 



