Article: The gymnosperm Archaeopteridium tschermakii and an associated glandular fructification from the Upper Visean Drybrook Sandstone of Great Britain
Archaeopteridium tschermakii (Stur) Kidston is described from compressions and fusainized material from the Puddlebrook locality of the Drybrook Sandstone of Gloucestershire. Fronds are up to 400 mm long and bifurcate, bearing oval to rounded pinnules on pinnae varying in complexity according to their position on the frond. Pinnules have a prominent surface pattern with several veinlets entering the pinnule base which divide and extend to the pinnule margin. Fusainized pinnules show evidence of longitudinal ridges and furrows, an ornamented cuticle, sunken stornata, veinlets comprising trachciiis with circular bordered pits and sub-epidermal fibre elements with annular or spiral thickenings. Two fronds are associated with twenty-four and eleven synangiaie organs respectively. Two isolated synangia are fusainized. Synangia are described as the new genus Cornutheca and are cone-shaped with a surrounding wall bearing numerous capitate glands enclosing a central area with 9-75 acuminate, slightly curved sporangia. The synangia are borne terminally on a slender, cruciate branch system. The possibility that Cornutheca was the pollen organ of Archaeopteridium is discussed and synangium diversity among Lower Carboniferous putative gymnosperms considered.