UPPER MISSISSIPPIAN AND PENNSYLVANIAN 



MEGASPORES AND OTHER PLANT 



MICROFOSSILS FROM ILLINOIS 



MARCIA R. WINSLOW 



ABSTRACT 



A preliminary investigation of land plant megaspores and other resistant plant parts 

 from the plus 65-mesh maceration residues of coals and carbonaceous layers of upper 

 Mississippian (Chester Series) and Pennsylvanian age indicates that plant megaspores 

 are useful in correlation, especially on a local scale, and may in the future aid in de- 

 lineating coal swamp heterosporous plant distribution. 



The study established that megaspore assemblages of Chester age are dominated by 

 spinose lageniculate and fibrous-coated megaspores representing an arborescent lepido- 

 dendrid-lepidocarp flora. Megaspores of the Caseyville Group indicate a more diverse 

 heterosporous flora, including both herbaceous and arborescent lycopsids. Spinose 

 lageniculate, fibrous-coated, auriculate, zonate, and deltoid-bladdered spores dominate 

 the assemblages. The oldest occurrences of sigillarians and medullosans are represented by 

 spinose aphanozonate and monolete spores, respectively. Sphenopsids also are represented. 



From the base of the Tradewater Group, to and including the Pope Creek Coal, the 

 assemblages are distinguished by their great diversity of zonate megaspores, by abundant 

 triangulate megaspores, and by the occurrence, apparently restricted, of one new genus. 

 The upper part of the Tradewater Group is characterized by smooth lageniculate spores, 

 abundant monolete medullosan spores, and by the lowest occurrence of spores with lateral 

 bladders. 



The assemblages from the Summum (No. 4) Coal to the top of the Carbondale Group 

 are characterized by an abundance of smooth aphanozonate spores of sigillarian alliance, 

 but, except for the absence of zonate spores, are otherwise similar to those of the Trade- 

 water Group. The assemblages of the McLeansboro Group, not investigated extensively, 

 appear to be characterized by heavy-apexed, smooth lageniculate-type spores, smooth 

 aphanozonate spores, auriculate spores, monolete medullosan spores, both deltoid- and 

 lateral-bladdered spores, and by the absence or extreme rarity of the fibrous-coated spores 

 and zonate spores. 



Zonation of megaspores from upper Mississippian and Pennsylvanian coals is pos- 

 sible, based on the differentiation of lageniculate spores, restricted ranges of some spores, 

 and, in some instances, marked variation in abundance. 



INTRODUCTION decreased in frequency as distance from the 



., . . ,, old shoreline increased. As the plants 



The spores described here are actually , , t , , n 1 



. f changed or evolved, more or less parallel 

 the resistant outer coats or the spores or °, , . , , . , , . - 



, ,. _ , l morphological changes took place in the 



propagative bodies of the gametophytic ^ ^ The ^ q£ fo J ^ and 



generation of certain types of land plants Uen {n beds of yo is therefore 



that were abundant in the floras of Mis- q£ yalue {n ^ torrdation of coals and 



sissippian and Pennsylvanian age. A great other sedimentary rocks as we H as for pos- 



vanety of spore types were produced in sible pa i e obotanical implications. 



large numbers and widely dispersed, prin- Coals of Mississippian and Pennsylvanian 



cipally by wind and water. Eventually they age are composed largely of more or less 



were entombed in both continental and ma- chemically altered fossil remains of plants, 



rine sediments, although they were pro- such as the woody parts of stems and 



duced only b\ land plants. Such spores oc- branches, resins, waxes, cork, cuticle, and 



curred in greatest numbers closest to their spore coats. Although spore coats do not 



site of production, and in marine sediments make up the bulk of the coal, except in 



[7] 



