Cheilanthes villosa Davenp
Cheilanthes villosa Davenp. ex Maxon
(Latin: villosus, softly hairy)
Local names: villous lip fern
Rhizomes compact; leaves clustered, 7–30 cm long; petioles usually dark brown, rounded on upper surface; leaf blades oblonglanceolate to ovate, 1.5–5 cm wide, 3–4-pinnate at base, the pinnae not articulate, the ultimate segments round to oval, bead-like, the largest 1–2 mm long, glabrous on lower surfaces except for a few coarse hairs, villous with coarse, unbranched hairs on upper surfaces; scales on underside of costae conspicuous (see below); n = 2n = 90, apogamous (Windham & Rabe 1993). Rocky slopes, cliffs, crevices, usually but not exclusively on limestone; widespread in the Trans-Pecos (e.g., Correll & Correll 30644, TEX-LL, Brewter Co.) including w of the Pecos River in Val Verde Co.; AZ, NM, and TX; also n Mexico. Sporulating summer–fall. The combination of large ovate-lanceolate to deltate scales on the lower side of the costae and scattered curly hairs on the upper side is distinctive for this species (Mickel & Smith 2004). The scales on the underside of the costae are particularly striking—they are often whitish, very large (2 mm wide), spreading, and nearly cover the underside of the ultimate segments; they are even visible when viewing the leaf from above. This species is an apogamous triploid, but is reported to hybridize with C. eatonii (Lellinger 1985; Mickel & Smith 2004), also considered to be apogamous in North America (Windham & Rabe 1993). Several TX specimens (Correll & Correll 12915, Val Verde Co., BRIT, TEX-LL; Correll & Correll 12906, TEX-LL) seem intermediate between C. villosa and C. eatonii and such morphological intermediates between the two have been reported from both w TX and NM (Windham & Rabe 1993); they have been referred to as C. pinkavii Reeves (but that name is not validly published). Although apogamous triploids are not self fertile (rather, sporophytes are produced through vegetative growth of gametophyte tissue without the fusion of eggs and sperm), the gametophytes can have functional antheridia and sperm can be produced. The sperm from these triploids can fuse with eggs from a different sexually reproducing species to form fertile hybrids (Gastony & Windham 1989). However, as noted by Windham and Rabe (1993), “recent gene exchange [between C. villosa and C. eatonii] is unlikely because both taxa are [currently] apogamous in North America.”