GROTE, PAUL J.1*, CHONGPAN CHONGLAKMANI2, and PRAMOOK BENYASUTA1. 1School of Biology, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; 2School of Geotechnology, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand. - Tertiary floras of Northern Thailand: charcoalified conifer wood.
Investigations have been made of charcoalified wood fragments from the
remains of a presumed ancient forest fire at Li Basin, Lamphun
Province, Northern Thailand, and thought to be of Late Oligocene or
Miocene age. The wood fragments are situated on a thick layer of
lignite in the Ban Pu Subbasin of the Li Basin, one of many Tertiary
basins extending from Northern Thailand, along the Malay Peninsula, to
Java and Sumatra. All wood fragments observed are from conifers. The
wood occurs as thin, tangentially compressed fragments, up to
approximately 3 cm long. Tracheids are long and slender (>1.7 mm
length by 21- 58 micrometers width). Bordered pits are arranged in a
single row or rarely in 2 opposite rows on radial and tangential walls
of the tracheids. Axial parenchyma and resin canals were not observed.
Rays are uniseriate, homocellular, reach a height of >40 cells,
consist of parenchyma cells, and lack ray tracheids. Crossfields show
one bordered pit in the tracheid wall, bordered pits not occurring in
the ray cells. Presence or absence of annual rings could not be
determined. The wood is assigned to the form genus
Podocarpoxylon, with possible affinity to Podocarpaceae. The
presence of these charcoalified remains may indicate a period in which
the lignite-forming swamp dried, at least locally, and supported a
grove of conifers subject to forest fire.
Key words: conifer, Podocarpoxylon, Tertiary, Thailand, wood