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DescriptionThis perennial fern consists of a few loose leaves that develop directly from the rootstock. The infertile leaves (including their petioles) are 1½–3' tall and erect or ascending, while the fertile leaves (including their petioles) are ¾–1½' tall and erect. Infertile leaves are more common than fertile leaves. The infertile leaves are yellowish green to medium green, hairless, and ovate in outline; they are deeply pinnatifid for the most part, although their tips are more shallowly pinnatifid, while their bases are more pinnate. The central stalk (or rachis) of each infertile leaf is winged. The spreading narrow lobes of the infertile leaves are generously spaced from each other; their margins are smooth to undulate and gently roll downward. Each infertile leaf has about 8 opposite pairs of these lobes; the upper lobes are ascending, the middle lobes are widely spreading, and the lower lobes are descending. The petioles of infertile leaves are usually shorter than their blades; they are light yellowish green to reddish brown and glabrous to slightly scaly. The infertile leaves persist all summer, but die down during the autumn in response to frost. The fertile leaves have a very different appearance. Their leaflets are contracted to form hardened structures that support the bead-like sporangia and their spores. In outline, each fertile leaf is ellipsoid-oblongoid, forming a narrow panicle of erect contracted leaflets with sporangia on a central stalk (or rachis). The fertile leaves become dark brown and persist through the winter into the following year. Eventually, the sporangia split open to release their spores; these spores are distributed by the wind. The root system consists of a stout smooth rhizome with spreading fibrous roots. This rhizome occasionally branches. Small clonal colonies of plants are often formed from the branching rhizomes.