Pteridium Gleditsch ex Scopoli (Dennstaedtiaceae) Earlier placement: Hypolepidaceae, Polypodiaceae

Bracken

Etymology Greek: pteron, a wing, from the shape of the pinnae, but the ancient Greeks used pteris for ferns in general. The word progresses to pteridion, a small fern.
Description Rhizome: long-creeping, jointed hairs.
Frond: deciduous, monomorphic.
Stipe: pale green, glabrous above with soft hairs at the brown base, vascular bundles: numerous, U- or O-shaped in cross section.
Blade: 2-4 pinnate, broadly deltate, large, papery to leathery.
Pinnae: lowest very large, costae rachis and costae grooved above, veins free, forked, except for a marginal strand.
Sori: continuous, along the margin, indusium: double, the outer false, reflexed, the inner distinct or absent.
Pteridium aquilinum
Pteridium aquilinum. Hairs, venation, false indusium.  BioImages: The Virtual Field-Guide (UK), photo Malcolm Storey.
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