An axis with a complex vascular system is detailed from Middle Triassic silicified peat of the Fremouw Formation of Antarctica. The diameters of the four specimens identified range from 1.2 to 2.2 cm; the longest specimen is approximately 12 cm. In transverse section, the vascular system of the silicified axis is divided into approximately 10 to 16 arms, which extend almost to its periphery. The vascular segments are embedded in parenchyma and occur as single traces or as segments connected in the center of the axis. These segments anastomose at varying levels within the axis. Ground tissue is located in the center of each segmented arm and consists of parenchyma and small diameter tracheids which are presumed to represent primary xylem. Secondary xylem borders this central ground tissue and extends completely around the segmented arms. A cambial zone is located external to the secondary xylem with poorly preserved secondary phloem to the outside. Traces are given off by the segments near the periphery of the axis; these consist of radially arranged secondary xylem, some with apparent external periderm. The anatomy of this axis most closely resembles the vascular tissue arrangement of plants belonging to the Cladoxylales (Devonian-Lower Carboniferous), but the anatomical differences, in addition to the stratigraphic age, preclude formal assignment to this or other orders.

Key words: anatomy, Antarctica, Cladoxylales, Triassic