i 9 , 5 ] AASE—MEGASPOROPHYLLS OF CONIFERS 289 



Between the ovules of the lower sporophylls is found an out- 

 growth which suggests an ovule with a poorly developed nucellus. 

 At each side of and behind this median outgrowth are others which 

 are more bractlike. In some of these xylem cells are present. 

 Whether these abnormal excrescences mean reversions to ancestral 

 features may be difficult to determine. The young strobilus shows 

 no such outgrowths. 



CUPRESSINEAE 



The general features of the ovulate strobilus in the Cupressineae 

 are the great reduction in the number of the sporophylls, the cyclic 

 arrangement of the sporophylls, complete coalescence of bract 

 and scale, and erect ovules variable in number. 



The strobilus of Cupressus Benthamii (figs. 58-70) is composed 

 of four decussate pairs of sporophylls. Many erect ovules are 

 packed at the base of each sporophyll. At the megaspore mother 

 cell stage the only evidence of the scale is a slight elevation back 

 of the ovules and the differentiation of the scale supply near the 

 strobilus cylinder. In somewhat later stages the free part of the 

 scale projects outward almost as prominently as that of the bract. 

 Contact and interlocking of epidermal cells takes place between 

 neighboring sporophylls in such a way that the ovules become 

 entirely inclosed. 



The vascular anatomy is slightly variable in the individual 

 sporophylls of a strobilus. As in other cyclic forms, the cylinder 

 gap fails to close after the departure of the appendage vascular 

 supply, and hence is continuous with the one above and below. 

 The bract supply may arise as a single strand at one side of the 

 continuous gap, or as two, one from each side of the gap, in which 

 latter case the two unite into one. The scale supply originates as 

 two bundles, one from each side some distance above the bract 

 supply. In other cases two bundles, one from each side of the gap, 

 compose both bract and scale supply. A strand may be given off 

 from one of the bundles to form the bract bundle, or a strand may 

 be given off from each bundle and the two strands unite to form the 

 bract bundle. Whatever may be the origin, the bract bundle 

 remains undivided to the tip of the bract. The scale bundles divide 



