Pellaea glabella Mettenius ex Kuhn

Smooth cliff brake

Etymology Glabella describes being rather smooth.
Description Rhizome: short-creeping or erect, orange-brown scales.
Frond: 35 cm high by 8 cm wide, evergreen, monomorphic, blade/stipe ratio: 1:1.
Stipe: dark purple to black, shiny, rounded above, croziers sparsely hairy at emergence, then glabrous, vascular bundles: 1.
Blade: usually 2-pinnate at the base, less above, linear, leathery, rachis glabrous or very sparsely hairy in some subtaxa.
Pinnae: 4 to 9 pair, bluish-green, lower pinnae stalked, upper sessile, a terminal pinna like the upper lateral ones; pinnules sessile or nearly so; margins entire; veins obscure.
Sori: oblong or linearly joined, submarginal, indusium: false, inrolled margins, sporangia: pale brown, maturity: early to late summer.
Culture Habitat: limestone substrates. Distribution: eastern North America, disjunct north-central North America and the Rocky Mountains. Hardy to -35°C, USDA Zone 3.
Distinctive Characteristics Similar to P. atropurpurea, but differing in monomorphism, smaller size, and particularly the glabrous stipe and rachis.
Pellaea glabella subsp. glabella Mettenius ex Kuhn
Pellaea atropurpurea (Linnaeus) Link var. bushii Mackenzie
Pellaea atropurpurea (Linnaeus) Link var. occidentalis E. E. Nelson
Pellaea glabella subsp. occidentalis (E. E. Nelson) Windham
Pellaea glabella var. nana (Richardson) Cody
Pellaea glabella var. occidentalis (E. E. Nelson) Butters
Pellaea occidentalis (E. E. Nelson) Rydberg
Pellaea pumila Rydberg
Pellaea glabella subsp. missouriensis (G. J. Gastony) Windham
Pellaea glabella subsp. simplex (Butters) A. Löve & D. Löve
Pellaea glabella var. simplex Butters, Amer. Fern J. 7: 84. 1917
Pellaea atropurpurea (Linnaeus) Link var. simplex (Butters) C. V. Morton
Pellaea occidentalis (E. E. Nelson) Rydberg subsp. simplex (Butters) Gastony
Pellaea suksdorfiana Butters
Pellaea glabella
Pellaea glabella.  Illustration by Edgar Paulton, from How to Know the Ferns and Fern Allies, John T. Mickel, © 1979 Wm. C. Brown Co.
Subtaxa Chaos in Taxonomy-ville, a deduction from the list of synonyms. Four taxa are distinguished, sometimes at the species level, sometimes subspecies, and sometimes varieties. The basis is in chromosome counts and scattered hairs on the midrib of terminal segments. See the Flora of North America for more.
Pellaea glabella
Pellaea glabella. a) fronds, b) fertile pinnae  Illustration by V. Fulford from Ferns and Fern Allies of Canada, William J. Cody and Donald M. Britton, 1989, © Agriculture Canada.
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