530 



BOTANY 



PART II 



of 



growth of the 



by a lateral bud which continues the direction 

 synipodial axis, displacing the cone to one side. 



The cones consist of numerous siDorophylls arranged spirally on 

 the axis. The microsporophylls bear large numbers of microsporangia 

 on the lower surface (Fig. 499). The macrosporophylls of the cone- 

 bearing Cycadaceae are considerably modified as compared with Cycas, 

 and each bears two marginal macrosporangia (Fig. 500) ; only in 

 Stangeria are the macrosporangia situated on the lower surface. For 

 the developmental history of. p. 507. 



Order 2. Ginkgoinae 



The single representative of the Family of the Ginkgoaceae which forms this 

 order is Ginkgo hiloba. This tree comes from Japan but is often seen in cultivation 

 in Europe, The [long-stalked leaves are divided dichotomously into two or more 



Fid. 501. — G'mktjo biloba. Male branch with flower; the leaves are not yet full gmwii. a, h, 

 Stamens ; '•, female flower ; d, fruit ; r, stone of same ; /, stone in cross section ; g, in longi- 

 tudinal section showing the embryo ; /(, female flower witli an exceptionally large number 

 of ovules borne on separate stalks. (Male flower and c, nat. size ; </, slightly reduced ; the 

 other llgures magnilied. After Richard ; a-d after Eichlek.) 



lobes aud are shed annually. The flowers are dioecious. The numerous stamens 

 are situated on an elongated axis which bears no enveloping leaves. Microsporangia 

 with an " cndolhecium " (cf. p. 483). Macrosjiorangia in i)airs at tlie summit of sliort 

 shoots ; sporophylls reduced to a collar-like outgrowth around the ]>as(! of the 

 sporangium (Fig. 501). Developmental history cf. ]). 508. 



