igS 



MORPHOLOGY OF GYMNOSPERMS 



sporophyll. The evidence from "abnormalities," which may be 

 interpreted as reversions, together with the testimony of the vascular 



Fig. 225. — Ginkgo biloba: abnormalities in ovulate structure; a, bud; b, nearly 

 normal strobilus; c, leaf with irregular thickenings; d, leaves bearing ovules; /, thicken- 

 ing at base of ovule; g, longitudinal striation along the fleshy part of the seed. — After 

 Fujil (17). 



anatomy, strongly support the view that the stalk is a stem bearing 

 two megasporophylls (collars), each of which bears a single ovule. 

 The development of the ovule has been investigated by Miss 

 CarotHers (46), from material grown in northern Ohio. About 

 the first of April no ovules are visible in the buds on the dwarf shoots, 



