Asplenium platyneuron (L.) Oakes

Ebony spleenwort

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 -30C, 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
Asplenium platyneuron
Asplenium platyneuron. Early June, current year's taller, vertical, fertile fronds, last year's shorter, decumbent, sterile fronds. New sterile fronds will arch.  Ray Edwards, 2004.
Asplenium platyneuron
Asplenium platyneuron. a) habit, b) fertile pinnae.  Illustration by V. Fulford from Ferns and Fern Allies of Canada, William J. Cody and Donald M. Britton, 1989, Agriculture Canada, used with permission.
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