Cheilanthes yavapensis

Cheilanthes yavapensis T. Reeves ex Windham
(for the type locality in Yavapai Co., AZ)

Local names: Yavapai lip fern, graceful lip fern

Very similar morphologically to C. wootonii; rhizomes long-creeping; leaves scattered; petioles dark brown; leaf blades oblong-lanceolate to nearly ovate, 2–6 cm wide, 4-pinnate at base, the pinnae not articulate, the ultimate segments round to oblong, bead-like, the largest 0.4–1 mm long, glabrous on lower surfaces or with a few scales near base, glabrous on upper surfaces (though appearing sparsely pubescent); scales on underside of costae lanceolate, conspicuous, often concealing the ultimate segments when viewed from below; n = 2n = 120 (Windham & Rabe 1993); spores averaging > 64 μm diam. (Windham 1993e). Rocky slopes, ledges, typically on igneous materials; known in TX only from El Paso Co. (Franklin and Hueco Mts.) (e.g., Correll 13790, BRIT, TEX-LL, Correll 15096, TEX-LL, G.M. Soxman 361, TEX-LL, Warnock & Johnston 16179, 16181, 16275, SRSC, all ident. by M.D. Windham who named the species; Yarborough & Powell 2002); AZ, NM, and TX; also nw Mexico. Sporulating summer–fall. Recent molecular analysis (able to identify genome source) shows that this species is an apogamous tetraploid containing genetic material from three species, with the maternal parent being C. lindheimeri and the other two genomes being derived from C. fendleri, and C. covillei, a species that occurs in Mexico and the sw U.S. to the w of TX. (Grusz et al. 2009). Grusz et al. (2009) also provided “compelling” evidence that C. yavapensis has “multiple origins” from these three parental species—in other words, there are two cryptic taxa. Some C. yavapensis have two copies of the C. covillei genome and one each of the C. fendleri and C. lindheimeri genomes, but some individuals have two of C. lindheimeri and one each of C. covillei and C. fendleri. Although such a multiple origin might be an argument for recognition of two different species, Grusz et al. (2009) noted that preliminary observations show the two types of C. yavapensis to “differ only slightly in morphology. For practical purposes of identification, they may prove impossible to differentiate.” We are thus only recognizing a single species for this genetically complicated entity. Yavapai lip fern is morphologically similar to C. wootonii and has sometimes been included as a part of that species. However, Windham and Rabe (1993) have noted that the similarities are due to “convergence rather than common ancestry,” and Grusz et al. (2009) have confirmed that C. wootonii was not involved in the origin of C. yavapensis. Unfortunately, although they have different origins and very different chromosome numbers (120 vs. 90 in C. wootonii), Grusz et al. (2009) pointed out that, “Despite evidence that C. wootonii and C. yavapensis are distinct entities, they remain difficult to distinguish by superficial observation of morphological traits” and that identification can be “particularly difficult” in TX. Likewise Windham and Rabe (1993) noted, “These characteristics [separating C. wootonii and C. yavapensis] can be subtle, and some specimens will be difficult to place in either C. wootonii or C. yavapensis.” Yarborough and Powell (2002) indicated that the species is “rare” in TX. Because of its rareness and limited distribution in the state, we consider this species to be of conservation concern in TX.

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