Filicalean ferns from the tertiary of western north America: Osmunda L. (Osmundaceae: Pteridophyta), Woodwardia sm. (Blechnaceae: Pteridophyta) and onocleoid forms (Filicales: Pteridophyta)
Recently discovered frond remains assignable to Osmunda wehrii Miller (Osmundaceae), as well as several new records of Woodwardia (Blechnaceae), and a new onocleoid fern are reported from the Tertiary of western North America. Pinnule morphology of O. wehrii supports the inclusion of this species in Osmunda subgenus Osmunda, as originally proposed by Miller and suggests a close affinity to O. regalis L. and O. japonica Thunb. New occurrences of the Woodwardia aerolata clade are noted for the Late Paleocene of western North Dakota and of a highly reticulate-veined form from the Miocene of western Washington. Re-evaluation of specimens of W. deflexipinna H. Smith (Succor Creek, Miocene) confirms its close affinity to W. virginica J. Smith. A fern with onocleoid anatomy is recognized from the middle Eocene Clarno Nut Beds of Oregon. Together, these examples demonstrate that the presence of critical taxonomic features, even in fragmentary remains, can increase our knowledge of filicalean fern evolution, biogeography and ecology in the Tertiary.
Biological and Environmental Sciences
Pigg, K.B., DeVore, M.L., & Wehr, W.C. (2006). Filicalean ferns from the tertiary of western north America: Osmunda L. (Osmundaceae: Pteridophyta), Woodwardia sm. (Blechnaceae: Pteridophyta) and onocleoid forms (Filicales: Pteridophyta). Fern Gazette, 17(5), 279-286.