igi 5 ] AASE—MEGASPOROPHYLLS OF CONIFERS 305 



of the gap. Two bundles from the sides of the gap unite to form a 

 semicircle which ends at the base of the ovule. 



Taxineae 



Perhaps the most outstanding features of the Taxineae in this 

 connection are the distinctly terminal ovule in some forms and the 

 development of the aril in the later stages. 



In TaxHS baccata (figs. 187-196) the bud of the primary fertile 

 and dwarf branch develops in the axil of a leaf of a long branch of 

 the first season's growth; the second season the ovule matures. 

 Near the tip of the primary fertile and dwarf branch is a secondary 

 dwarf branch bearing a few decussate pairs of bracts and termi- 

 nally an ovule. Occasionally two secondary dwarf ovule-bearing 

 branches are produced, one at each side of the terminal vegetative 

 bud of the primary branch. Beneath the ovuliferous branch or 

 branches the primary shoot is covered with scalelike bracts. The 

 growth of the terminal vegetative bud of the primary shoot is 

 usually arrested by the active development of the secondary ovulif- 

 erous branch, so that the latter appears to be terminal. Ovules 

 are found maturing on the second, third, and fourth seasons' 

 growth, instead of on the second season's only. This implies that 

 the ovule in some cases fails to mature the second season, or that 

 the vegetative bud of the primary dwarf branch may resume 

 activity and produce other ovuliferous branches; the latter seems 

 most probable; also the presence of branch scars on the older and 

 more elongated dwarf shoots suggests that the latter conclusion 

 may be drawn. 



After the bundles to the upper sterile bracts have either passed 

 into their respective appendages or have ended before entering 

 the latter, the vascular supply of the axis of the ovule-producing 

 branch consists of four bundles. These bundles unite in pairs, 

 one bundle from each side of the bract bundle of the next lower pair, 

 and not one from each side of the bract of the last pair as is usually 

 the case where the united bundle is to supply some axillary struc- 

 ture. The xylem creeps around the phloem in each of the two 

 bundles formed. Sometimes one of the four bundles in the axis 

 ends, whereupon the odd bundle behaves like the fused bundle 



