Investigations of Angiosperms from the Eocene of North America: Leaves of the Engelhardieae (Juglandaceae)

Abstract

Foliage of the Engelhardieae (Juglandaceae) is common in the Tertiary of southeastern North America and Europe. A comparative analysis of the cuticle, venation, and gross morphological features of the leaves and leaflets of the three extant genera in the Engelhardieae indicates that they can be resolved into only two groups. Engelhardia and Oreomunnea-Alfaroa complex, based on foliar characters. Because the fossil leaves are similar to those of the Oreomunnea-Alfaroa complex, thus not assignable to either extant genus, and because several different engelhardioid fruit types are often found together with the fossil leaves, the new genus Oreoaroa is proposed for these fossils. A new species [O. claibornensis ] from the Middle Eocene of Tennessee and Kentucky is described and compared with similar fossil foliage from Europe. The geographic and stratigraphic distribution of Oreoroa suggests that Oreomunnea and Alfaroa had their origin from a southeastern North American-European complex. [Oreoroa orsbergensis comb. nov. (Bantisia orsbergensis Wesssil et Weber) is also proposed.].