A NEW FOSSIL OAK WOOD FROM IDAHO

Abstract

ALTHOUGH SEVERAL hundred species of fossil oaks from the United States have been described from their leaf impressions, comparatively little work has been done on the fossil wood of the genus. This neglect may be attributed in part to the uncertainty of specific differentiation on the basis of characters of the wood anatomy, since positive identification of oak species often cannot be made from wood structure alone. However, the sub-genera of the genus Quercus may be determined by the microscopic examination of their wood anatomy, and many of their included species also may be identified by this means. Thus it seems reasonable that well preserved specimens of fossil wood might be expected to show similar distinctions. Most of the work on fossil oak wood has been done by German investigators who described a number of western American species as well as European ones. This work is so little known that Trelease (1924), in monographing the oaks of America, stated that the only fossil oak wood to receive a specific name was Quercus Marcyana Pen., although at that time more than a dozen species had been described. However, the descriptions of these oaks might have been overlooked very easily since they were not published in widely distributed journals. The first description of fossil oak wood was published in 1839 by Goppert, who described fossil wood from Silesia and northern Germany and named it Klidenia quercoides. At that time he mentioned the nearly complete agreement of K. quercoides and Quercus pedunculata and six years later changed the generic name to Quercites, the genus in which fossil leaves of oak are now placed. However, Unger in 1842 had proposed the genus Quercinium for fossil oak wood and had pointed out that probably Klodenia Gopp. should be changed to Quercinium. Very little notice was taken of the genus until Felix (1883, 1884) published the descriptions of the species known at that time and added four new ones. In the first of these papers he showed that the three species previously described by Unger were based on invalid characters and therewith included them in the group of species upon which he published. Penhallow (1891) described a fossil wood from the post-glacial of Illinois that strongly resembled the modern chestnut oaks and named it Quercus Marcyana, disregarding the established generic name Quercinium. Knowlton (1899) published a description of a new species, Quercintium lamarense, and nothing further appeared in the literature until Platen (1908) added five new species to the genus. Since that time little has been published except for two reports by American workers on fossil woods from California, one of which was apparently identical with the modern Quercus agrifolia. These woods were given the generic name