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Key to Pellaea

Pteridaceae

Pellaea

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1 Petiole straw-colored, tan, or gray, not lustrous; rhizome scales lanceolate to ovate, > 0.3 mm wide.
1 Petiole dark brown to black, lustrous; rhizome scales linear or subulate, < 0.3 mm wide.
  2 Petioles terete, glabrous or pubescent; rhizome scales uniformly orangish-brown, entire.
    3 Petioles and rachises sparsely to densely pubescent, dull; pinnae long-stalked, those toward the base of the leaf on stalks 5-15 mm long; [of a variety of substrates, including non-calcareous]
      4 Rachises densely puberulent with short, curly hairs; ultimate leaf segments (at least the larger) > 30 mm long; spores averaging < 62 μm in diameter
      4 Rachises sparsely pubescent with long, divergent hairs; ultimate leaf segments < 30 mm long; spores averaging > 62 μm in diameter
    3 Petioles and rachises glabrous to very sparsely pubescent, shiny; pinnae sessile or short-stalked, those toward the base of the leaf on stalks 0-4 (-6) mm long; [strictly of calcareous substrates]
  2 Petioles slightly grooved or flattened, glabrous; rhizome scales with a blackish median stripe and pale brown margins, obscurely toothed.
          6 Ultimate leaf segments thin in texture, overall flattish (though the margins revolute), acute to acuminate at the apex, but lacking a mucro or cusp.
          6 Ultimate leaf segments leathery, strongly 'rolled', mucronate at the apex.
               8 Leaves oblong to elliptic in outline; pinnae either ternate toward the base of the leaf and simple toward the tip of the leaf, or all simple; primary leaf segments 5-10× as long as wide (unflattened); [known from outcrops in the upper Piedmont of SC]
               8 Leaves usually narrowly triangular in outline; pinnae usually pinnate toward the base, becoming ternate to simple toward the tip; primary leaf segments 3-5× as long as wide (unflattened); [known from outcrops in Piedmont of NC]