There are a large number of varieties, differing chiefly in the form and division of the pinnae; var.
cambricum (originally found in Wales) has the pinnae themselves deeply cut into narrow segments; var.
cristatum is a handsome variety with fronds forking at the apex and the tips of all the pinnae crested and curled.
long, including the stalk; it is characterized by having the lower pinnae of the frond deflexed; it is generally distributed in Britain, though not common.
The solitary seed has no perisperm or albumen, but has two large and curiously crumpled cotyledons concealing the plumule, the leaves of which, even at this early stage, show traces of pinnae.