The stem, Buteoxylon gordonianum gen. et sp. nov. was found in stratified ash-beds at Oxroad Bay, near Tantallon Castle. It consists of a terminal region, about 12 cm in length surrounded by 38 petioles borne at acute angles on the stem in a ⅖ phyllotactic spiral. The stelar anatomy resembles that of a Calamopitys with a mixed pith. The petiolar bundles, however, have a distinctive T-shape in cross-section unlike any known species of Calamopitys.

Associated with this fossil stem are numerous seeds of Tantallosperma setigera gen. et sp. nov. These are radially symmetrical, with four (rarely five or six) integumental lobes joined at grooves on the body of the seed but free apically where they bear numerous bristle-like hairs. The funnel-shaped salpinx is only slightly narrower than the lagenostome. Enclosed spherical pollen grains have a trilete mark and measure 60 μ in diameter. The average dimensions of the seeds are 5·9 × 1·1 mm.