Arborescent gymnosperms from the Viséan of East Kirkton, West Lothian, Scotland

Abstract

Plants of gymnospermous affinities are the most important component of the flora at East Kirkton. Four genera of anatomically preserved gymnosperm stems with well developed secondary xylem are interpreted as arborescent. The largest specimens (trunks up to 50 cm in diameter) are attributed to the genus Pitus. Features of the wood, including ray size, are characteristic of the species Pitus withamii Lindley & Hutton which has long been described from the Strathclyde (former Oil-Shale) Group of Scotland. Decorticated axes of Eristophyton fasciculare are more common; their study has enlarged our concept of the species with regard to maximum diameter, internode length and phloem organisation. Similarly, the decorticated specimens of Bilignea solida Kidston found at East Kirkton exceed in diameter the original material described from Ayrshire. The fourth taxon is Stanwoodia recently described by Galtier and Scott (1991). In all these plants, features of leaf traces suggest that leaves were relatively large and densely borne on ultimate branches. These leaves were shed ultimately, prior to a later phase of wood development; they certainly correspond to (? most of) the compression foliage commonly found in association: Sphenopteridium, Adiantites and Spathulopteris.