XL] 



GINKGO 



ovules at the summit, one on each side of the actual apex. Fre- 

 quently one of these is larger than the other. The occasional 

 occurrence of abnormal female flowers is interesting from the 

 point of view of palaeobotanical comparison. In extreme cases 



Fig. 631. Gingko biloba. A, A', B. Microaporophylls and sporangia. C. Seed 

 with the outer flesh removed showing an exceptional, tricarinate (radiospermic), 

 form. D. Abnormal megasporophyU ; a, vegetative bud; c, collar. E, F. 

 Tracheids from a stem. G. Transverse section of a leaf -vein; px, proto- 

 xylem, t, transfusion-tracheids. (A, B, after Seward and Gowan; D, after 

 Fujii.) 



the partially modified lamina of a fohage-leaf may bear marginal 

 ovules, the lamina being continuous with the collar (fig. 631, D, c) 

 at the base of the ovule. In other cases the peduncle may give 

 off several stalked ovules, as in the specimen described by Fujii^ 

 1 Fujii (96); Seward and Gowan (00) B. PI. ix. figs. 1— .5; Sprecher (07) p. 138. 



