Myriopteris lanosa, the hairy lip fern, is a medium-sized fern of the eastern United States. The leaves are twice-divided into lanceolate or oblong segments, and are sparsely covered in hairs, but lack scales, hence its common name. One of the cheilanthoid lip ferns, it was usually classified in the genus Cheilanthes as Cheilanthes lanosa until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows in shallow, dry, soil, often in rocky habitats.
Description Leaf bases are closely spaced along the rhizome, which is generally 4 to 8 millimeters (0.2 to 0.3 in) in diameter and rarely branched. The rhizome bears persistent scales, which are linear to slightly lanceolate, distantly toothed, straight or slightly twisted, and loosely pressed against the surface of the rhizome. Most of them are brown in color, but at least a few will show a thin, dark central stripe, which does not stand out well from the rest of the scale color. The fronds spring up in clusters and emerge as fiddleheads (circinate vernation). When mature, they are 7 to 50 centimeters (2.8 to 19.7 in) long and 1.5 to 5 centimeters (0.59 to 1.97 in) wide. Fertile and sterile fronds are similar in appearance. The stipe (the stalk of the leaf, below the blade) is 3 to 18 centimeters (1.2 to 7.1 in) long. It is dark brown to purplish-black in color, with many long, persistent, dark-jointed hairs. The upper surface is rounded.
The leaf blades range in shape from lanceolate to linear-oblong. The blade is usually bipinnate-pinnatifid (cut into pinnae and lobed pinnules) at the base. Each blade is cut into 12 to 20 pairs of pinnae. The rachis (leaf axis) is rounded on the upper side, dark in color, and bears soft hairs of uniform shape, but not scales. The pinnae are not jointed at the base, and the dark pigmentation of the rachis enters the edge of the pinnae. The pinnae at the base of the leaf are slightly smaller than the pinnae immediately above them, and the pinnae are more or less symmetric about the costa (pinna axis). The upper surfaces of the pinnae are sparsely covered with hairs. The upper sides of the costae are brown for most of their length and lack scales. The pinnules are lanceolate or oblong, and not bead-shaped as in some other species of Myriopteris. There are 7 to 14 pairs of pinnules per pinna. The largest pinnules are 3 to 5 millimeters (0.12 to 0.20 in) long, with a sparse covering of long, segmented hairs on both upper and lower surfaces. On fertile fronds, the sori are protected by false indusia formed by the edge of the leaf curling back over the underside. The false indusia look similar, though not identical, to the rest of the leaf tissue, and are 0.05 to 0.25 mm wide. Beneath them, the sori do not form long lines, but are discontinuous and concentrated on lobes at the tip and sides of the pinnule. Each sporangium in a sorus carries 64 spores, typical of sexually reproducing species within the genus. The diploid sporophyte has a chromosome number of 2n = 60.
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