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Key to Sceptridium

Ophioglossaceae

Sceptridium

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1 Sterile leaves usually 2 per plant, the petiole prostrate and the blade therefore held flat on the ground; root smooth, yellowish; ultimate leaf segment about as wide as long, subflabellately veined, lacking a midrib; sporulating Jan-Apr; [section Hiemobotrychium or genus Holubiella]
1 Sterile leaf 1 per plant, the petiole erect or ascending and the blade usually held aerially; root irregularly ribbed, blackish; ultimate leaf segment fan-shaped, obovate, longer than wide, pinnately veined, the midrib weakly developed; sporulating Jul-Oct; [section Sceptridium or genus Sceptridium s.s.].
  2 Sterile leaf 4-pinnate-pinnatifid, finely divided, the ultimate segment lacerate and linear, < 3 mm wide
  2 Sterile leaf 2-pinnate to 4-pinnate, not finely divided, the ultimate segment ovate or oblong, most or all of them > 8 mm wide.
    3 Sterile pinnae entirely divided into short, round or acute pinnule; lateral pinnule with an inconspicuous and poorly-developed central vein; plant producing 1 or 2 leaves per season.
      4 Sterile pinna and pinnule apices round to obtuse; ultimate segment cuneate, rounded, or truncate at the base; ultimate segment remote or overlapping; [VA and KY southwards]
      4 Sterile pinna and pinnule apices obtuse to acute (rarely round); ultimate segment mostly rounded at the base, not fan-shaped, ovate or oblong; ultimate segment often crowded and overlapping; [NJ, PA, w. VA, w. NC, WV, and OH northwards]
    3 Sterile pinnae (or their terminal portion) elongate (the sides often nearly parallel), entire to shallowly lobed, not divided into pinnule; lateral pinnule with a conspicuous and well-developed central vein; plant producing 1 leaf per season.
        5 Sterile pinna and pinnule apices obtuse to rounded (to somewhat acute); ultimate segment mostly ovate, narrowly ovate, or oblong, mostly about 2× as long as broad or less; overwintering leaves green, not bronze
        5 Sterile pinna and pinnule apices acute; ultimate segment mostly oblong or lanceolate-oblong, often > 2× as long as broad; overwintering leaves bronze (or green if covered by leaves).
          6 Sterile blade mostly 2(-3)-pinnate, herbaceous in texture; ultimate blade segment mostly oblong to obliquely lanceolate, the margin nearly parallel, the base cuneate, the apex relatively blunt
          6 Sterile blade mostly 3-pinnate (or more divided, those forms keyed above), leathery in texture; ultimate blade segment trowel-shaped, the margin usually not parallel, the base truncate or obtuse, the apex relatively pointed