THE CARBONIFEROUS FLORA. 



137 



uro which, as I have already mentioned, appears on a 

 minute scale in the twigs of the fir-tree, and that some- 

 times casts of these piths in sandstone appear in a separate 

 form, constituting what have heen named Sternbcrgim or 

 Artisiw. As Renault well remarks with reference to 

 Cordaites, the existence of this chambered form of pith 

 implies rai)id elongation of the stem, so that the Cordaites 

 and conifers of the coal-formation were probabl}' quickly 

 growing trees (Fig. 62). 



The same general statements may be made as to the 

 coal-vegetation as in relation to that of the Erian. In 





'* *WWW„„ 



't»lniftrilf'^ff}ftfttl' 



a 



a 



CL 



Fio. 62. — Sternhergia pith of Dadoxylon. a, Specimen (natural size), 

 sliowinj; renmins of wood at a, <t. b, Junction of wood and pith, inag- 

 nifled. c, Culls of the wood of do., a, «; 6, medullary ray; c, arco- 

 lation. 



the coal period we have found none of the higher ex- 

 ogens, and there are only obscure and uncertain indica- 

 tions of the presence of endogens, which we may reserve 

 for a future chapter ; but gymnosperms abound and are 

 highly characteristic. On the other hand, wo have no 

 mosses or lichens, and very few Algse, but a great num- 

 ber of ferns and Lycopodiaceae or club-mosses (Fig. 03). 

 Thus, the coal-formation period is botunically a meeting- 

 place of the lower phjBnogams and the higher cryptogams, 

 and presents many forms which, when imperfectly known, 

 have puzzled botanists in regard to their position in one 

 or other series. In the present world, the flora most akin 



