Article: A late Silurian flora from the Lower Old Red Sandstone of south-west Dyfed

This extensive compression flora from the late Silurian (Downtonian) of South Wales contributes to our understanding of terrestrial vegetation relatively early in the colonization of the land by predominantly vascular plants. The large number of fertile Cooksonia specimens has resulted in an amplified diagnosis of C. hemisphaerica Lang for which mtraspecific variation is demonstrated; in the erection of a new species, C. cambrensis, and in records of plants close to C. caledonica and C. pertonii. Elongate sporangia on unbranched twisted stalks are named Tortili-caulis transwalliensis gen. et sp. nov. and affinities with bryophytes and vascular plants are discussed. Hostinella is the commonest stem type, but some smooth axes show departures from dichotomous branching. In addition, axes with triangular and truncated spines are described indicating, together with the above, a diversity of taxa and morphological organization. A short progress report on our studies of the early history of vascular plants in the South Wales area is presented.