GYMNOSPERMvE. 



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by intercalated veinlets. The Ginkgo presents in many respects a simpler organisation 

 than the rest of the Coniferae, and its study is therefore likely to bring us nearer to the 

 starting-point of the Order than that of any other genus. 



Ginkgo is the largest-leaved of the Coniferae. The leaf is fan-shaped on a long and 

 slender petiole, and the fan is generally more or less cleft in the centre and sometimes 

 still further subdivided. There are two fibro-vascular bundles in the petiole from which 

 fine dichotomosing veins proceed. Filling in between the veins there is beneath the epi- 

 dermis a " lacunary " tissue formed of elongated cells, arranged in transverse bands which 

 anastomose together. The same construction prevails in Cycads, and a not dissimilar one 



Fig. 41. — Leaves and female organs of Ginkgo. A. Bilobed leaf of ordinary type. B. Short lateral and 

 flower-bearing branch, surmounted by a rosette of entire leaves and stems supporting recently fer- 

 tilised ovules, c. Stem bearing a cluster of ovules on pedicels, only oue of which is destined to be 

 developed. D. Stalk bearing two ripe seeds, of which one has been removed to show the scar of 

 attachment. E and F. A bicarinated and a trigonal seed with their fleshy envelopes removed. Half 

 the natural size. After Saporta and Marion. 



in Cordaites. The sexual organs are disposed on abbreviated lateral shoots. The male 

 flower-spike is in form of a catkin, and axillary, each of the altered leaves of which it is 

 composed bearing two or three terminal pollen-sacs at their ends, which depend from 

 short peduncles, as in other Taxece and in Cordaites. The female apparatus is placed 

 amidst a rosette of normal leaves, and consists of a group of petioles, supporting each two 

 ovules instead of a bilobed leaf. The matured seed is more like, in structure, that of 

 Cycas and of Cordaites, already described, than that of any other Conifer. Under a 

 fleshy integument there is a hard testa in form of a bi- or tri-carinated nut, the large 



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