A New Species of Sawdonia with Notes on the Origin of Microphylls and Lateral Sporangia

Abstract

A new species of Sawdonia is described from Middle Devonian rocks of northern New Brunswick. The fossils consist of compressions in which axial emergences and sporangia are well preserved. The emergences vary considerably in size and form and are found on both axes and laterally borne sporangia. The sporangia are about 4 mm in diameter and contain large numbers of spores. The plant differs from the only previously described species, S. ornata, in the nature of the emergences on the axes and their presence on the sporangium wall. We also have more information concerning the spores than is presently available for S ornala. A brief review of other microphyllous plants is included with reference to the evolution of the microphyllous leaf.