Changes in the flora
The composition of the flora changed during the Westfalian D. Most striking
was the decline of the arborescent lycopods (Lepidodendron,
Sigillaria, etc). This had probably to do with the disappearance of
the vast marshes. Only a few arborescent lycopods, being better adapted to
dryer circumstances, continued their existence into the Permian.
Moreover the incline of the seedfern trees is striking. The large
leaved seedferns were decreasing, whereas the smaller leaved, sometimes
liane-like forms became relatively commoner in the Stephanian.
The peltasperms, of which Autunia (formerly Callipteris)
is the better known genus, is a new group of seed ferns.
The most successful group was that of the conifers (e.g. Walchia),
which started to dominate the woods. Members of this group are the most
frequently found fossils in the Permian sediments.