282 BOTANICAL GAZETTE [October 



Investigation 



Abietineae 



The ovulate strobilus in all the Abietineae is composed of a 

 comparatively large number of sporophylls. The sporophyll 

 here is obviously composed of two organs. In some forms, as Kete- 

 leeria and Pseudotsuga, each of the three-pronged bracts is reflexed 

 over the scales below, giving the strobilus a bristly appearance; 

 while in others, as Cedrus Libani, the bract is a minute flap, and 

 its bundle dies before it reaches the free portion. Between these 

 two extremes are many intermediate forms. That the bract is a 

 modified leaf seems evident at least in some genera. In Pseudo- 

 tsuga and Larix there is a gradual transition from ordinary foliage 

 leaves to bracts of a well developed sporophyll; and in abnormal 

 cones of Picea, Larix, etc., the bracts are like the vegetative leaves. 

 The scale is well developed in all the Abietineae. 



The vascular anatomy of the megasporophyll is less variable 

 in the different genera of the Abietineae than is the case in any of 

 the other five groups. 



In the lower one-third or more of the strobilus of Pinus marilima 

 and P. Banksiana there is a general sterilization, beginning with 

 failure of the ovules to produce seed, followed lower down by the 

 abortion of the ovules, and finally at the base of the strobilus the 

 reduction in size and final disappearance of bract or scale or both. 

 In P. Banksiana the bract disappears before the scale, but both 

 are finally lost, and between the lowest ovuliferous scales and the 

 bud scales is a region where the strobilus stalk is smooth except 

 for slight elevations (fig. 2). Each of these elevations is supplied 

 with a small vascular strand and suggests a vestige of a megasporo- 

 phyll. In P. maritima only the scale suffers reduction and loss, 

 and the bract, reduced throughout the strobilus, increases in size 

 toward the base (fig. 1). 



Correlative with the sterilization and reduction of the append- 

 ages in the lower portion of the strobilus are variations in mode of 

 origin of their vascular supplies (figs. 3-29). In the upper half 

 of the strobilus the bract supply originates as a single bundle at 

 the base of the cylinder gap. The scale originates as three or four 

 bundles instead of two as in other Abietineae, one at each side of the 



