THE PENNSYLVANIAN PERIOD. G01 



attained a length of six feet and a width of half a foot. They were 

 preserved in great abundance and make up a large part of some beds 

 of coal. The leaf-structure combined characters now possessed by 

 certain conifers, with others possessed by certain cycacls. Palisades 

 were sometimes well developed, though sometimes replaced by water- 

 storage tissues. In one form observed, the leaf had a distinctly fleshy 

 character, as if adapted to xerophytic life. 1 The floral organs were 

 peculiar to the family and have been worked out with marvelous suc- 

 cess, even the structure of the pollen having been determined. The 

 inflorescence took the form of separate male and female catkins, 

 arranged on slender stalks attached to the stem between the leaves. 

 The seeds (Cardiocarpus) were of the cycadian rather than of the 

 conifer type, and were very abundant and sometimes winged, with 

 a view to wind transportation. In the working out of the structure 

 of the cordaites, it has been shown that many fossils referred, on account 

 of the wood structure, to conifers (e.g. Dadoxylon, Araucarioxylori) , 

 are cordaitean, and that the forms known as Artisia or Sternbergia 

 are casts of the pith-cavity of cordaites; and not a few other mis- 

 interpretations have been corrected. 



The transfer of so many supposed conifers to the cordaites leaves 

 it doubtful whether any true conifers are recorded from the Carbon- 

 iferous, though they were probably represented in the Permian. Numer- 

 ous seeds are found in Carboniferous beds that cannot certainly be 

 referred to cordaites or other known forms, some of which may belong 

 to conifers. As previously remarked, the upland vegetation is not 

 known, and it is not impossible that conifers, a type specially suited 

 to an upland habitat, prevailed there. 



Cycads have been commonly reported from the Carboniferous, 

 but the evidence remains inconclusive; the same may be said of the 

 ginkgos. There is no evidence whatever of angiosperms. 



The Distribution of the Carboniferous Flora. 



The Coal flora of North America and that of Europe were strikingly 

 similar, implying close geographic relations and like conditions. Nearly 

 all the genera, and about one third of the species, were identical. In 

 part at least, this flora extended to high latitudes in the environs of 



1 Scott, Studies in Fossil Botany, p. 425. 



