PHANEROGAMIA 501 



Ginkgoaceae (Baicra) make their appearance, with another type referred to the 

 Conii'erae ( Ullmannia). 



The Cordaiteae disappear in the Rothliegende. The Gymuosperm flora can be 

 followed througli the Trias, in which it consisted of extinct types of Cycadineae, 

 Ginkgoineae, and Coniferae (Voltzia, in the Bunter Sandstone), to the Jurassic 

 period. In the latter it attained a great development in that both the Ginkgoineae 

 and the Cycadineae attained their maximum development and were represented 

 by numerous forms. True Araucarieae also appear in the Jurassic ; on this 

 account, as well as on account of their organisation, this group may be regarded as 

 the oldest of the existing Coniferae. 



In the Wealden Cycadineae and Ginkgoineae, along with some Coniferae, were 

 dominant among the Gymnosperms. On passing to the Cretaceous strata the 

 ancient types are found to be reduced, while the Coniferae become more numerous. 

 Among the latter existing genera appear (Dammara, Sequoia, Pinus, Cedrus, 

 Abies, Callitris, etc.). The Taxaceae also appear to be represented, but the remains 

 are of uncertain affinity. 



The Tertiary Gymnosperms belong entirely to existing types and for the most 

 part to existing species. The Coniferae are dominant ; the Ginkgoineae are repre- 

 sented only by Ginkgo biloba, but this occurred in Europe along with other species 

 now limited to Eastern Asia or North America (Cryptomeria japonica, Taxodium 

 distichum, T. hetcrophyllum, Sequoia yiyantca, S. sempervirens, Pinus Strobus 

 etc.). One Cycadaceous plant (Enccphalartos) is also known. 



CLASS II 

 Angiospermae ( 10 ) 



The differences between gymnospermic and angiospermic plants 

 are well and shortly expressed by saying that the seeds of the former 

 are naked, while those of the latter are enclosed in a cavity. Only 

 a detailed account of the structure of the angiospermic flower will, 

 however, make the relations existing between the two great classes 

 of Phanerogams clear. 



The Angiospermie Flower. The male and female .sporophylls of 

 Gymnosperms were borne in distinct flowers or even on different 

 individual plants, and the flowers had no special envelope. In 

 Angiosperms, on the other hand, a union of the two sexes in the one 

 flower which is thus HERMAPHRODITE and the investment of the flower 

 by coloured leaves (differing in appearance from the foliage leaves) 

 forming a PERIANTH is the rule. In contrast to the UNISEXUAL or 

 DICLINOUS flower with the sporophylls arranged spirally on an 

 elongated axis, which is characteristic of the Gymnosperms, the 

 perianth leaves and sporophylls in the Angiosperms are usually borne 

 in whorls on a greatly shortened axis. THE ARRANGEMENT OF THE 



FLORAL LEAVES IN WHORLS, THE COLOURED PERIANTH, AND THE 

 II KRM APHRODITE NATURE OF THE FLOWERS ARE THUS CHARACTERISTIC 



