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1 Fronds (4-) 6-15 (-20)× as long as wide; angle of pouch 25-50°
..2 Angle of pouch 70-120°; tract of elongated cells running between median line and the edge of lower wall of the pouch; area of air spaces within frond rarely longer than wide
..2 Angle of pouch 45-90°; tract of elongated cells running along or close to the edge of the lower wall of the pouch; area of air spaces within frond mostly longer than wide