Pliocene Nothofagus Wood from the Transantarctic Mountains

Subfossil wood fragments up to 10 cm long and 2 cm in diameter recovered from a locality thought on the basis of diatom deposits to be upper Pliocene-lower Pleistocene (Oliver Bluffs, Sirius Formation, 85°1 O'S., between 1800 and 1900 m in the Transantarctic Mountains) were sectioned for identification. Degradation prevented observation of some wood features, but others were well preserved. All of the fragments appear to represent one species. Features of growth rings (ring porous, vessels mostly solitary in earlywood), rays (predominantly uniseriate, both erect and procumbent cells common), vessel perforation plates (simple, at least in earlywood), lateral wall pitting of vessels (predominantly transitional in earlywood, scalariform in latewood) and tyloses (present) permit one to identify the Oliver Bluffs woods as a Nothofagus. Wood sections of Nothofagus from New Guinea, New Caledonia, Tasmania, and southern South America were prepared in order to secure a more precise identification. The Oliver Bluffs woods very closely matches N. betuloides from Tierra del Fuego and southern Chile as well as N. gunnii from Tasmania in qualitative and quantitative features. Original data on wood of these Nothofagus species are presented. The nature of the Oliver Bluffs woods is discussed with relation to reports of Nothofagus wood from the Falkland Islands and Nothofagus pollen from Antarctica, and the implications of this polar flora are considered.