Cheilanthes eatonii

Cheilanthes eatonii Baker
(for its discoverer, A.A. Eaton, 1865–1908)

Local names: Eaton’s lip fern

Rhizomes compact; leaves clustered, 6–35 cm long; petioles dark brown, rounded on upper surface; leaf blades oblong lanceolate, 1.5–5 cm wide, 3–4-pinnate basally, the pinnae not articulate, the ultimate segments oval to round, bead-like, the largest 1–3 mm long, densely hairy to nearly glabrous above (the hairs usually whitish or grayish, but sometimes reddish), densely tomentose on lower surfaces; costae and/or rachis with conspicuous scales on lower surface, but these not concealing the lower surface of ultimate segments; n = 2n = 90, 120, apogamous (Windham & Rabe 1993). Rocky slopes and ledges; mainly Edwards Plateau and Trans-Pecos with outliers in Morris (Correll & Correll 12480, BRIT, TEX-LL) and Cherokee (Correll 35220, TEX-LL) cos. in the ne part of East TX and Wilson Co. (Turner et al. 2003) in the sw corner of East TX; also Brown Co. (HPC; Correll 1956) in the sw part of the Cross Timbers and Prairies and Mitchell Co. (Correll 1949, 1956) in the Rolling Plains; mostly sw U.S. (AR, AZ, CO, NM, OK, TX, UT), disjunct from AR (Baxter and Benton cos.—Taylor 1984; where now locally extinct, J. Peck, pers. comm.; Peck 2011b) to isolated stations in VA and WV (Knobloch & Lellinger 1969; a disjunction of ca. 650 mi/1046 km); also Mexico and Costa Rica. Sporulating Mar–Nov. [C. castanea Maxon, C. eatonii forma castanea (Maxon) Correll, C. tomentosa var. eatonii (Baker) Davenp.] The disjunct occurrences in ne TX are the result of isolated appropriate rocky microhabitats in an area where such environments are quite rare. For example, a Cherokee Co. collection (D.S. Correll, 35220, TEX-LL) was from “crevices of iron-ore rock,” while the Morris Co. collections (D.S. Correll & H.B. Correll 12438, BRIT, TEX-LL; Correll & Correll 22480, BRIT) were made on “Slope of mountain, on iron ore rocks” and “On rocks on mountain.” This is one of a number of ferns found primarily in the sw or w U.S. with isolated disjunct populations in the southern Appalachians (see discussion on page 31). It is a highly variable species composed of both apogamous triploids and tetraploids “of unknown parentage” (Windham and Rabe 1993). We are following Correll (1956) and Windham and Rabe (1993) in treating C. castanea as a synonym of C. eatonii. Correll (1956) noted that when extreme forms of typical C. eatonii and what he considered to be forma castanea are found “they are so distinctive that one would immediately consider them to be specifically different. Unfortunately, very little material of extreme f. castanea exists in herbaria. An overwhelming amount of material does exist, however, which grades into one or the other of these two forms. It is simply an arbitrary matter as to which category they should be relegated to.” Correll (1956) “placed all plants which have all or part of their fronds tending to be glabrescent [when mature] on the upper surface of their segments into f. castanea” and treated “those plants with segments hoary and densely tomentose above as the typical form.” Windham and Rabe (1993) noted, “Because there is no clear morphologic break, C. castanea is placed here in synonymy under C. eatonii pending further study.” The species is reported to hybridize with C. villosa (Lellinger 1985; Mickel & Smith 2004); individuals that appear to be morphological intermediates between the two are known from w TX and NM (Windham & Rabe 1993); see discussion under C. villosa. It is also closely related to and similar to C. tomentosa, but with scales of costae linear-lanceolate to lanceolate (versus linear, hair-like and inconspicuous). It is “one of the most common ferns in mountainous areas of the Trans-Pecos” (Yarborough & Powell 2002).

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