Netted veins along the axes of the blade to form a series of areoles (enclosed spaces) or a single continuous vein along which the sorus is borne, elongate sori with indusia opening toward midvein. Here 2 genera.

Blechnum Linnaeus

Deer fern

Etymology Greek: Blechnum is derived from the word blechnon, which is an ancient Greek word for ferns in general.
Description Rhizome: erect to creeping, scales brown or black.
Frond: evergreen, dimorphic, fertile leaves more erect and longer than sterile leaves.
vascular bundles: more than 2 vascular bundles arranged in arc.
Blade: pinnatifid to 1-pinnate, ovate, leathery, young fronds are often red.
veins sterile:free, often forked; fertile: veins of fertile leaves united to form sorus-bearing secondary vein parallel to costa or costule.
Sori: elongate, continuous, on both sides of the costae, indusium: flap-like, opening towards the costa.
Distinctive Characteristics Emerging fronds in the genus are usually red or reddish, loosing the color when fully expanded.
Blechnum spicant. a) free venation in sterile pinna; b) netted venation of fertile pinna.  Illustration from Scandinavian Ferns by Benjamin Ĝllgaard and Kirsten Tind, Rhodos, 1993.

Woodwardia Smith

Chain fern

Etymology Named for Thomas Jenkinson Woodward, (1745-1820), an English botanist.
Description Rhizome: long-creeping, scales.
Frond: deciduous, monomorphic or dimorphic.
Stipe: scaly or not, vascular bundles: variable.
Blade: pinnatifid to 1-pinnate-pinnatifid, thin-textured, scales on emergence in W. areolata, but glabrous later.
veins free or partly netted.
Sori: in chainlike rows, but distinct, along the costae, indusium: flap-like, opening towards the costa.
Distinctive Characteristics Linear sori adjacent to the costae characterize Woodwardia.
W. virginica: chains of sori
Woodwardia is characterized by chains of sori as shown here.  Photo: Dennis Woodland

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