Notes on the Lepidocarpaceae 1 



James M. Schopf 



Introduction 



Members of the Lepidocarpaceae are characteristic of the Eur-American 

 floral province and are known to be present in both the Lower and Upper 

 Carboniferous. Both in western Europe and in America recent records have 

 added to our knowledge of this plant family, and it is now possible to present 

 a discusison of the classification and evolution of the groups included in the 

 lepidocarp alliance. It is the purpose of this paper to call attention to some of 

 the bio-characters 2 which appear to be important in distinguishing lepidocarp 

 genera but which have not been given equal consideration by different authors, 

 thereby leading to some ambiguities and conflicting conclusions. It is hoped 

 that this review will lead to greater consistency of treatment and to more rapid 

 progress in understanding the geological and biological history of this group 

 of plants. 



The writer wishes to acknowledge the help of Dr. J. Marvin Weller and 

 thank him for critically reading the manuscript. 



The Lepidocarp Family 



The Lepidocarpaceae, like many other families of fossil plants, represent a 

 group of indefinite taxonomic status. This family seems never to have been 

 formally diagnosed, and hence its taxonomic validity has not been established 

 beyond question — rather it has been a name denned through implications 

 lent by the genera included in it. In the writer's opinion it comprises a group 

 having undoubted natural affinity whose scope seems to be comparable to 

 certain families of modern plants. The Lepidocarpaceae can be defined briefly 

 as follows: 



Ligulate lycopsid plants, of arboreous or arborescent habit, producing male 

 and female fructifications separately (probably never in the same cone, nor in 

 juxtaposition on fertile branches equivalent to cones). Female fructifications 

 specialized so that individual sporophylls or parts of them have assumed the 

 essential characters of seeds in each of which only one megaspore normally 

 matures. Sporangium indehiscent in the sense that the seed megaspore is not 

 expelled; seed megaspore exceedingly large and lacking the thick impervious 

 type of spore coat that characterizes the megaspores of free-sporing lycopsids. 



A rather sharp distinction should be made between the lepidocarp family 



1 Published by permission of the Chief, Illinois State Geological Survey. 



2 A bio-character is considered to be a definable unitary feature that has hereditary 

 significance. 



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