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This perennial fern consists of several ascending leaves about 4-12" tall; the leaves are usually organized together in a loose tuft; they are deciduous. The leaf blades are 4-10" long and about one-half to one-third as much across; they are light green or yellowish green, hairless, and slightly membranous. The leaf blades are ovate to deltate-ovate in outline and broadest toward the middle or near their bases. The structure of each leaf blade is bipinnate-pinnatifid to pinnate-bipinnatid – the leaflets and their lobes tend to be less differentiated toward the tip of the leaf blade than at its base. There are about 8-12 pairs of leaflets along the rachis (central stalk) of each leaf; the leaflets are not necessarily opposite from each other. The leaflets are lanceolate or deltate-lanceolate in outline and their structure is simple-pinnate to pinnatifid, dividing into either subleaflets and/or lobes. The subleaflets are ovate to oval in shape and their margins are shallowly cleft and/or crenate; they are often abruptly contracted at their bases, forming distinct petiolules (basal stalklets). These subleaflets occur primarily along the lower to middle rachis (central stalk) of the leaf blade. Elsewhere, the leaflets are divided into lobes that are broadly oblong to ovate in shape and the margins of these lobes are cleft and/or crenate. The slender petioles are shorter than the leaf blades; they are light green to yellowish green and glabrous. The rachises (central stalks) of the leaf blades are similar to the petioles. The sori (spore-bearing structures) are located on the leaf undersides; they occur near the sinuses of the subleaflets and leaflet lobes. The sori are orbicular in shape; each sorus is partially covered by an indusium (pale protective membrane) that is 0.5 mm. across. The indusia soon fade away and they are replaced by the brownish sporangia containing the spores. These spores usually are released during the summer; they are distributed by the wind. Each spore is about 30 micrometers across; it is brown, globoid, and prickly. The root system consists of long hairy rhizomes, from which the leaves develop.


Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© John Hilty

Source: Illinois Wildflowers

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