Flora of an Illinois Coal Ball

Abstract

In the single coal ball described (Middle Pennsyl-vanian) were portions of plants that have hitherto been known from the Carboniferous of America only as impressions; they are Calamites communis, Sphenophyllum (plurifoliatum type), Bothrodendron, and Lyginopteris. Belonging to Bothrodendron are transverse sections of a stem tip, a megasporangium and microsporangium both containing spores. In the microsporangium the spores are in the tetrad stage, while in the mega-sporangium 4 megaspores were observed. The most striking feature in the comparison of Bothrodendron and Selaginella is the similarity of the 2, which suggests that Bothrodendron is the progenitor of the living Selaginel-las.