250 GINKGO. 



afforded sufficient reason for the institution of a separate 

 subdivision of the Gymnospenns in which to include Ksempfer's 

 genus. 



Ginkgo is sometimes spoken of as unknown in a wild condition, 

 but this statement has recently been challenged by Mrs. Bishop^ 

 (Miss Bird), who speaks of having "met with several fine 

 specimens in the magnificent forests which surround the sources of 

 the Gold River and the smaller Min in "Western China." x 



The genus Ginkgo, as represented by the single living species 

 Ginkgo biloba, may be diagnosed as follows : 



A tree of pyramidal form reaching a height of over 30 metres, 

 with smooth grey bark, characterized among existing Gymnosperms 

 by its flat, broad leaves, with the Cyclopteris type of venation, 

 deciduous in the autumn, possessing a long and slender petiole 

 slightly grooved on its upper surface and a lamina varying con- 

 siderably in size and shape, occasionally fan-shaped and entire, but 

 more frequently divided into two halves by a more or less deep 

 median division, or subdivided into several wedge-shaped lobes. 

 The foliage-leaves occur either scattered on long shoots or crowded 

 at the apex of short shoots ; the latter form of leaf -bearing axis 

 often passes by apical growth into the long shoots bearing scattered 

 leaves separated by long internodes. 



Flowers dioecious. The male flowers, which occur in the axils 

 of scale-leaves, have the form of a stalked central axis bearing 

 scattered, loosely disposed stamens ; each stamen consists of a 

 slender filament terminating in a very small apical scale, bearing 

 usually two, sometimes three or four, elliptical pollen-sacs which, 

 open by longitudinal dehiscence. The pollen - grains develop a 

 rudimentary prothallus consisting of a few cells, and before 

 fertilization two large spirally coiled multiciliate spermatozoids are 

 produced from the generative nuclei in the pollen-tube. The 

 female flowers usually have the form of a long peduncle bearing 

 two terminal elliptical ovules enclosed at the base by a collar-like 

 envelope representing a reduced carpellary leaf. Abnormal female 

 flowers, possessing more than two ovules, are not infrequently met 

 with. Each ovule consists of a nucellus enclosed by a single 



1 Letter to the London Standard, Aug. 17, 1899. Vide also Bird (80), vol. ii. 

 p. 144. 



