This type is distinguished by its large bipinnate fronds bearing long and narrow pinnae with close-set pinnules, characterized by the anastomosing secondary veins.
When the division is carried into the second degree, and the pinnae of a compound leaf are themselves pinnately compound, a bipinnate leaf is formed.
Mr Wieland has also described young bipinnate fronds, very like those of recent species of Zamia and Encephalartos, attached to a Bennettites stem, and exhibiting the vernation characters of many recent Cycads (fig.
Dorsetshire and in the Inferior Oolite beds of Yorkshire, as well as in Rhaetic strata in Persia and elsewhere; it is characterized by its bipinnate fronds, and may be compared with the recent Australian genus Bowenia - peculiar among living Cycads in having bipinnate fronds.
The Bunter sandstones of the Vosges have afforded several species of Lower Triassic plants; these include the Equisetaceous genus Schizoneura - a member also of the Glossopteris flora - bipinnate fern fronds referred to the genus Anomopteris, another fern, described originally as Neuropteris grandifolia, which agrees very closely with a southern hemisphere type (Neuropteridium validum, fig.
This Jurassic species bore bipinnate fronds not unlike those of the South African, Australian, and New Zealand Fern Todea barbara, which were characterized by a stout rachis and short broad pinnules bearing numerous large sporangia covering the under surface of the lamina.
In these plants the laminae or blades of the leaves are pinnate or bipinnate and are produced at the FIG.