Myriopteris tomentosa, formerly known as Cheilanthes tomentosa, is a perennial fern known as woolly lipfern. Woolly lipfern is native to the southern United States, from Virginia to Arizona and Georgia, and Mexico.
Description Woolly lipfern is a small evergreen fern, growing in tufts or clusters and bearing hairs on most of its leaf surfaces. The rhizome is compact and generally 2 to 3 millimeters (0.08 to 0.1 in) or 4 to 8 millimeters (0.2 to 0.3 in) in diameter and branching. It bears persistent scales 3 to 4 millimeters (0.1 to 0.2 in) long, which are linear to slightly lanceolate, straight or slightly twisted, and loosely pressed against the surface of the rhizome. They have a broad, dark, central stripe which is sharply differentiated from the narrow, light brown, orange-tan, or pale reddish-brown margins. The fronds arise from the rhizome in clusters. Unlike many ferns, they do not emerge as coiled fiddleheads (noncircinate vernation). When mature, they are 8 to 45 centimeters (3.1 to 17.7 in) long and 1.5 to 8 centimeters (0.59 to 3.15 in) wide. Fertile and sterile fronds are similar in appearance. The stipe (the stalk of the leaf, below the blade) is 5 to 20 centimeters (2.0 to 7.9 in) long. and typically about one-third of the total length of the frond. It is dark brown or chestnut brown in color, with a covering of woolly, orange-tan jointed hairs and hairlike scales. Its upper surface is rounded. The leaf blades are oblong-lanceolate. The blade is usually tetrapinnate (cut into pinnae, pinnules, pinnulets, and divisions of pinnulets) at the base. Each blade is cut into about 20 pairs of pinnae. These are opposite and widely spaced at the base of the blade, but are closer to one another nearer the tip of the blade. The blades are gray-green in color. The rachis (leaf axis) is rounded on the upper side, dark brown in color, and bears soft hairs of uniform shape, and scattered linear scales. The pinnae are not jointed at the base, and the dark pigmentation of the rachis enters the base of the pinnae. The pinnae at the base of the leaf are about the same size as the pinnae immediately above them, and the pinnae are more or less symmetric about the costa (pinna axis). The upper sides of the costae are green for most of their length. On their underside, they bear multiple rows of linear scales, not more than 0.1 to 0.4 mm wide, loosely overlapping, but not concealing the leaf surface, with a truncate base and without cilia at their edges. (This character distinguishes the species from the similar Myriopteris rufa, where the scales of the costa are broad and do conceal the leaf surface.) The smallest segments of the leaf are ovate and bead-like, as in many species of Myriopteris, up to 1 to 2 millimeters (0.039 to 0.079 in) in length. The upper surface of the leaf bears fine, soft, unbranched hairs, while the lower surface is covered with a mat of dense, woolly hairs. There are 6 to 11 pairs of pinnules per pinna. The fern shrivels up into a brown curled mass and appears dead in periods of drought but will revive in periods of moisture. On fertile fronds, the sori are protected by false indusia formed by the edge of the leaf curling back over the underside. The sori occur at the edge of the false indusium (where it folds over) or a short distance back from that point. The false indusia are somewhat different in appearance and texture of the leaf tissue, and are 0.05 to 0.25 mm wide. Beneath them, the sori are more or less continuous around the margin of the bead-like leaf segments. Each sporangium in a sorus carries 32 brown spores. The triploid sporophyte has a chromosome number of 90. Reproduction is apogamous: triploid spores are formed by mitosis, rather than meiosis, and grow into gametophytes, which sprout a genetically identical sporophyte without fertilization. It is quite similar to M. rufa, but that species has broader and more prominent costal scales, whereas those of M. tomentosa resemble hairs. Small specimens might be confused with M. gracilis, but that species has only hairs proper, rather than the narrow scales present in M. tomentosa.
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