Permineralized fruits and seeds from the Princeton chert (Middle Eocene) of British Columbia: Vitaceae

Abstract

Four permineralized vitaceous seeds are described from the Middle Eocene Princeton chert, Allenby Formation, British Columbia. Three distinct types of ruminate perchalazal seeds are recognized, one is described as a new species Ampelocissus similkameenensis Cevallos-Ferriz et Stockey sp.nov., while the remaining seeds are referred to as type 1 and type 2 seeds. Five integumentary zones are recognized in each seed: zone 1 is an outer zone of thin-walled rectangular to polyhedral cells; zone 2 is a zone of thick-walled sclereids; zone 3 is a zone of cells with spiral thickenings; zone 4 is a zone of rectangular thin-walled cells (when preserved); and zone 5 is a zone of tangentially elongated thin-walled cells with dark contents. The chalaza in seeds of A. similkameenensis and the type 1 seed has three distinct zones, while in the type 2 seed it contains cells similar to integumentary zone 2. These Princeton seeds illustrate that structural features of Eocene Vitaceae include characters unlike those of extant taxa. This information contributes to our knowledge of anatomical structure within the group as a whole and underscores the need for review of both fossil and extant Vitaceae. Paucity of vitaceous seeds in the Princeton chert compared to the large number of preserved aquatic and semiaquatic remains suggests that they represent plants that grew in a nearby environment. Abrasion of the integument suggests that like extant seeds, they may have been dropped after passing through the gut of a bird.