Abstract

The recorded history of Oklahoma's vegetation begins in the Cambrian Period some 750 million years ago and is traceable to the present. The earliest known fossil plants in the State are marine algae extensively exposed in the Arbuckle Mountains. Presently Oklahoma's oldest reported land vegetation is Devonian and one of the largest known Devonian tree fossils was found near Ada. During Carboniferous time coal-forming swamps were numerous and the ancient vegetation, now coal, has contributed much to the wealth of the State. Permian time was arid but a rich fossil flora indicates that the State was not entirely a desert as might be supposed from the redbed nature of most of the Permian rocks. In the latter part of the Mesozoic Era the vegetation evolved into modern types. Fossils of these are present in the Cretaceous rocks of northwestern Oklahoma. The early Tertiary vegetation was subtropical but toward the end of that time became more like that of the modern prairies. During the Glacial Period northern forests migrated southward and remained until the ice in the north was melted. The present vegetation is a complex of southern, western, eastern and northern floral elements. The accompanying is a summary of Oklahoma's vegetation through geological time.