Know Your Natives – Woolly Lip Fern

Woolly lip fern (Cheilanthes tomentosa*) of the Brake Fern (Pteridaceae) family, is an evergreen fern that becomes brown and shriveled during drought but revives with renewed moisture. The genus name combines Greek words for “lip” (cheilos) and “flower” (anthos), in reference to the location of the sori or “fruit dots” (see below). The specific epithet describes the plant’s pubescence: tomentose, from the Latin, meaning “with thickly matted hairs”. The common name “lip fern” refers to the smoothly under-turned margins of the pinnae (leaflets). Cheilanthes tomentosa is also called “resurrection fern”, a name that applies to several different species. In the U.S., woolly lip fern occurs across the southern states from Arizona to Virginia, as well as in southeastern Kansas and southern Missouri. It is absent from Louisiana, Mississippi and Florida. In Arkansas, it occurs in rocky elevated areas of the Interior Highlands of the northwestern half of the state. Its preferred habitat is dry soils on sunny rocky ledges and slopes, especially in crevices.

Photo 1: Woolly lipfern grows well in sunny rocky area. Photo – May 28.
Photo 1: Woolly lip fern grows well in sunny, rocky areas. Photo May 28.
Photo 2: The fern becomes dehydrated during dry conditions, but revives with renewed moisture. Photo – September 15.
Photo 2: The fern becomes dehydrated during dry conditions, but revives with renewed moisture. Photo September 15.

Woolly lip fern, a clumping fern with an erect rootstock, has a dense tangle of thin, wiry, fibrous roots. The rootstock supports an expanding thick cluster of intermixed living and dead leaves, in the ferns, generally known as fronds. Rootstocks of several individual plants may grow together. New silvery fronds, with down-folded apexes, appear in spring or during summer into fall in response to renewed moisture and even during winter with favorable temperatures. Mature fronds are a bluish to medium green on the adaxial side and a tannish light green on the abaxial side. They ascend from a central point in small plants or randomly in larger plants. In outline, fronds have a linear to lanceolate shape. Mature fronds survive winter temperatures while new fronds may freeze. Fronds remain alive for a year, the older ones dying out in late fall into winter. Pinnae (leaflets) of dying fronds, as well as those that become dry due to drought, curl inward from their sides and apexes. Dead fronds remain attached to the rootstock for years as they gradually disintegrate.

Photo 3: New, mature and dead fronds intermix to form a dense clump. New fronds emerge when moisture is available and temperatures are not freezing. Photo – December 14.
Photo 3: New, mature and dead fronds intermix to form a dense clump. New fronds emerge when moisture is available and temperatures are above freezing. Photo December 14.

Sori, the clusters of spore-producing sporangia, are borne on the abaxial (under) surface of fertile fronds (see below). The adaxial (upper) surfaces of fertile and infertile fronds are indistinguishable. Fronds are generally 8 inches to 16 inches long and 2 to 3 inches wide. Of the total frond length, the rachis (pinna-bearing midrib) tends to be about three times longer than the stipe (frond stalk). Fronds have 40 or so pinnae that are generally alternately arranged along the rachis; however, lower pinnae may be in sub-opposite or even opposite pairs. The largest pinnae tend to be near the middle of the rachis. Spacing between pinnae decreases distally until pinnae near the frond apex are in contact with each other.

Photo 4: Two infertile fronds are to the left (adaxial and abaxial sides shown). Two fertile fronds are to the right (adaxial and abaxial sides shown). Photo – December 14.
Photo 4: Two infertile fronds are to the left (adaxial and abaxial sides shown). Two fertile fronds are to the right (adaxial and abaxial sides shown). Photo December 14.

Dense white pubescence on new fronds gives them a silvery appearance. The pubescence extends around stipe and rachis, petiolules (stalks of pinnae) and costae (midribs of pinnae), as well as over both upper and lower pinna surfaces, though much denser abaxially. As fronds age, pubescence becomes light brown and thinner. Pubescence along the slender, stiff, round stipe and rachis may be scrapped off to expose a dark purple surface.

Woolly lip fern is a thrice-cut fern. Pinnae are more or less flat and tilted toward sunlight. In outline, they are ovate-lanceolate, broadest toward the middle and gradually narrowing to a rounded distal end. Pinna margins are incised with a dozen or so pairs of slightly off-set, apically rounded pinnules (sub-leaflets). The longer pinnules are further cut proximally into apically rounded, oval lobes. Margins of pinnae and pinnules curve from adaxial to abaxial surface to form a narrow continuous lip along the abaxial side.

Photo 5: Display shows abaxial side of an infertile frond (left) and fertile frond (right). In this December 7th photo, outlines of the developing sori can be seen on the right frond. Note the tan pubescence that extends from the rachis onto the costae and pinnae.
Photo 5: Abaxial surfaces of an infertile frond (left) and fertile frond (right). In this December 7th photo, outlines of the developing sori can be seen on the fertile frond. Note the tan pubescence that extends from the rachis onto the costae and pinnae.

Sori, in bumpy linear strips, are adjacent to and slightly covered by the marginal lip. A true indusium (sorus cover) is lacking. Mature sori are smooth and black. Spores, dispersed by breezes, are released in summer.

With spores having been dispersed, the above-ground “diploid sporophyte phase” of a fern’s life cycle (referred to as “alternation of generations”) concludes. In the soil, spores germinate to produce a prothallus, the “haploid gametophyte phase”. For most ferns, the prothallus produces mobile sperm gametes and attached egg gametes, allowing fertilization of the egg and development of a new diploid sporophyte plant. However, woolly lip fern is apogamous–zygotes form without fertilization.

Photo 6: In this May 21st photo, sori are well developed. Note lipped margins and change of pubescence from tan to white. The dense pubescence hides the purple rachis.
Photo 6: In this May 21st photo, sori are well developed. Note lipped margins and change of pubescence from tan to white. The dense pubescence hides the purple rachis.

In a garden environment, woolly lip fern would add texture and character throughout the year. It is one of few ferns that grows well in sunny, dry, rocky sites–a nice selection for rock gardens or for crevices of a rock wall. In an especially favorable site, numerous new plants may appear. Should older plants become unattractive, due to retention of dead fronds, clumps not in crevices are easy to remove. Woolly lip fern survives drought and is not favored by deer.

Four other lip ferns occur in Arkansas; namely, Alabama lip fern (Cheilanthes alabamensis), Eaton’s lip fern (Cheilanthes eatonii), slender lip fern (Cheilanthes feei), and hairy lip fern (Cheilanthes lanosa). Woolly and hairy lip ferns are the two most common lip ferns in the state. Hairy lip fern is significantly smaller than woolly lip fern, and it has less dense pubescence. Additionally, to distinguish woolly lip fern from the other lip ferns, woolly lip fern has 1) a coarser appearance, 2) an erect clumping growth habit, 3) tomentose stalks and pinnae, and 4) alternate pinnae.

Photo 7: Hairy lipfern (lower in photo), smaller than woolly lipfern, has fewer more widely spaced pinnae. In this photo of December 14th, pubescence had been mostly worn away.
Photo 7: Hairy lip fern (lower in photo), smaller than woolly lip fern, has fewer more widely spaced pinnae. In this photo of December 14th, pubescence had been mostly worn away.

* Some authorities classify woolly lip fern as Myriopteris tomentosa.

Article and photographs by ANPS member Sid Vogelpohl

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