Etymology From the Greek platy, broad or wide + neuron, nerves or veins, which is inexplicable and inappropriate, from an exaggerated early drawing.

Description Rhizome: erect, short, scales clathrate, dark brown to black, to 4 mm.
Frond: 40 cm high by 4 cm wide, evergreen, somewhat dimorphic, fertile fronds stiff, erect, earlier, sterile prostrate, only to 10 cm, blade/stipe ratio: 3:1 to 5:1.
Stipe: at first green, then reddish-brown, lustrous all the way to the end of the rachis, dark brown to black, filiform scales at base, then glabrous, vascular bundles: 2 C-shaped, back to back, uniting to 1 upwards in an X-shape.
Blade: 1-pinnate, linear, widest above the middle, tapering to either end, commonly with tiny glandular hairs and a few linear scales.
Pinnae: 25 to 45 pair, alternate, fewer pair on sterile fronds, pinnae eared upwards, also sometimes downwards, oblong, but lowest pinnae short, triangular; margins finely crenate or serrate; veins free.
Sori: linear, 2 mm, 1--12 pairs per pinna, paired across the midrib, herringbone-style, indusium: white or translucent, on one side of the sorus, sporangia: brown, maturity: late summer.

Culture Habitat: rock ledges and walls, on limestone, and terrestrial on subacid soil, light shade to sun. Distribution: eastern North America, disjunct in Arizona, and, hold your hat, South Africa. Hardy to -30°C, USDA Zone 4.

Distinctive Characteristics The reddish-brown color of stipe and rachis is the source of the common name.

Synonyms
Acrostichum platyneuron L.
Asplenium platyneuron (L.) Britton, Sterns & Pogg.
Asplenium ebenum Ait.
Asplenium platyneuron var. bacculum-rubrum (Fernald) Fernald
Asplenium platyneuron var. incisum (E. C. Howe) Robinson