I30 



MORPHOLOGY OF GYMNOSPERMS 



cylinder of the cone axis and branch, so that usually there are found 

 in the stalk of the sporophyll four bundles, the two outer ones of which 

 supply the two ovules (fig. 126). The bundle passing to the ovule 

 divides twice before the outer and inner vascular systems of the ovule 

 are established. Miss Stopes (44) finds that the inner system 

 belongs to the inner fleshy layer of the integument rather than to the 

 nucellus, because the bundles, especially in Cycas, continue in the 

 inner fleshy layer beyond the 

 free portion of the nucellus 



Fig. 126. — Stangeria paradoxa: 

 diagram of the vascular system of 

 the megasporophyll. — After WoRS- 

 ■ DELL (27a). 



Fig. 127. — Cycas circinalis: diagrammatic 

 longitudinal section of nearly mature seed; o, 

 outer fleshy layer, with a bundle (o') of the outer 

 vascular system; s, stony layer; i, inner fleshy 

 layer, with a bundle (j') of the inner vascular 

 system; c, central vascular strand. — After Miss 

 Stopes (42). 



and extend into the free por- 

 tion itself. She concludes 

 also that these bundles, in the simplest cases, are the branches of a 

 single central strand, only a few branches coming from the side 

 bundles (fig. 127). The relation of the inner and outer sets of 

 vascular strands to the bundles of the sporophyll may be seen by 

 studying figs. 128-131, taken from Matte's monograph on the 

 vascular anatomy of cycads (40). 



The vascular bundles of the sterile portion of the sporophyll above 

 the ovules are generally mesarch, as in the foliage leaves; and in the 

 bundles of the outer fleshy layer of the integument the mesarch 



