Article: Permineralized ovulate cones of Lebachia from late Palaeozoic limestones of Kansas

A diverse assemblage of permineralized conifer remains has been discovered in late Palaeozoic limestones from the mid-continent of North America, near Hamilton, Kansas. Ovulate cones described as Lebachia lockardii sp. nov., support the structural homologies among cordaites, primitive conifers, and modern conifers proposed by Florin, and reveal anatomical features that are remarkably similar to those of many extant conifers. Features not recognized from previously described cones of Lebachia are dorsiventral, bilaterally symmetrical fertile shoots, inverted orientation of the ovules, and the true bilateral symmetry of the ovules. In both morphological structure and cuticular features the specimens show more variability than has previously been documented for a single conifer species, and this calls to question the reliability of features previously employed for generic separation of Lebachia from Ernestiodendron. The specimens also provide the first histological evidence for ovule abscission in Palaeozoic gymnosperms, and allow for the interpretation of several aspects of ovule ontogeny and early conifer reproductive biology.