Fruits of Mastixioideae (Cornaceae) from the Paleogene of western North America

Endocarps representing the subfamily Mastixioideae of the Cornaceae commonly occur in the European Tertiary, but have only been reported in North America from the Middle Eocene Nut Beds Flora of the Clarno Formation of Oregon. We report the occurrence of a new species of Mastixia endocarp from the Late Eocene of California, and transfer Mastixioidiocarpum oregonense (Scott) Manchester of the Clarno flora to Mastixia oregonense. We also describe two incompletely preserved endocarps of Mastixia species from Paleocene and Eocene localities in Wyoming. Finally, we describe Langtonia bisulcata Reid and Chandler from the Late Paleocene of Wyoming and provide an emended description of Mastixicarpum occidentale Manchester from the Clarno flora. In sum, these occurrences indicate that the Mastixioideae were widespread in the early Tertiary of western North America.