INVESTIGATIONS OF TERTIARY ANGIOSPERMS: A NEW FLORA INCLUDING EOMIMOSOIDEA PLUMOSA FROM THE OLIGOCENE OF EASTERN TEXAS

Abstract

A new fossil flower and inflorescence‐bearing locality has been discovered in the Oligocene of the Texas Gulf Coast. The new flora is similar to the Middle Eocene Claiborne Flora of the southeastern USA, but the quality of preservation is sometimes better in the Oligocene fossils. One component of the new flora, a mimosoid legume inflorescence, appears identical with Eomimosoidea plumosa , first reported from the Claiborne Formation of western Tennessee. Investigations of these younger specimens indicate that the taxon had changed little during the Middle Eocene‐Oligocene interval, and the better quality of preservation of the Texas specimens has provided further insights into the structure of the fossils. Comparisons of the fine structural details of the pollen of Eomimosoidea with similar pollen of extant mimosoids has confirmed that the fossil genus is indeed extinct and suggests that tetrahedral tetrads of columellate, tricolporate pollen grains are ancient, possibly primitive, in the Mimosoideae.