AASE—MEGASPOROPHYLLS OF CONIFERS 



287 



gradually approaches a circle, and in a slightly older bud closes 

 to form the cylinder of the shoot. The bud is united with the bract 

 at its base, and the general appearance of a young bud and its 

 subtending bract is suggestive of a young abietinean sporophyll. 

 In Keteleeria Fortmici (figs. 36-57), one bundle originates near 

 the base of the gap in the strobilus cylinder and supplies the bract. 

 It remains undivided throughout its course. Two bundles, one 



Figs. 30-35. — Pinus Baiiksiana, vegetative bud: fig. 30, radial longitudinal 

 section of lower portion of young vegetative branch; a vegetative bud in axil of each 

 bract except at base of branch; fig. 3 1 , origin of bract (b) and bud bundles; figs. 32-35, 

 transverse sections, young bundles of bud beginning to form cylinder of branch; X 16. 



from each side of the gap, supply the scale. The two bundles 

 soon unite, forming one inverted bundle, that is, its xylem faces 

 the xylem of the bract. The inverted bundle then breaks, forming 

 a semicircle of bundles which spread and divide, forming in the 

 scale a row of sixteen or more bundles. Near the ovular insertion 

 a small concentric branch is given off to each of the two inverted 

 ovules. 



