Fruits from the mid-cretaceous of north america with pollen grains of theclavatipollenitestype

Abstract

Abstract Small fruits with clumps of monocolpate, reticulate pollen grains of the Clavatipollenites type adhering to the stigmatic surface have been recovered from mid-Cretaceous (early Cenomanian) Potomac Group sediments of eastern North America. They provide the first megafossil evidence of this important early angiosperm pollen genus. The fruits are described as Couperites mauldinensis gen.et sp. nov. They are unicarpellate and unilocular containing a single, anatropous and pendulous seed. The fruit wall is thin with distinct, tubercular protrusions enclosing spherical resin bodies. The seed wall is apparently composed of two distinct tissues, indicating that the seed was probably derived from a bitegmic ovule. The outer tissue consists of one layer of cuboid palisade cells, the inner tissue consists of longitudinally elongated cells. Fruit and seed characters indicate that Couperites is more closely related to Chloranthaceae than to any other magnoliid family, and support the systematic affinity suggested for most dispersed Clavatipollenites taxa. However, the anatropous seeds place Couperites outside the current circumscription of the family and imply a more basal phylogenetic position.