Cheilanthes angustifolia Humb., Bonpl. & Kunth
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Authority
Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.
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Family
Pteridaceae
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Scientific Name
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Description
Species Description - Rhizomes compact, horizontal, 2–3 mm diam.; rhizome scales linear-lanceolate, concolorous, castaneous to black, lustrous, 2.5–3 mm long, entire; fronds 12–32 cm long, clumped; stipes 1/2–2/3 the frond length, castaneous to blackish, lustrous, grooved, glabrous or with sparse 0.3–0.5 mm hairs and linear, brown scales; blades deltate, 2–3-pinnate, basal pinnae usually largest, 5–12 x 3.5–9 cm (length:width ratio 1.3–2:1), glabrous on both sides; pinnae (5–)7–10 pairs (apical 4–5 pinna pairs entire, median 2–6 pinna pairs pinnate, basal 0–1 pair bipinnate), terminal segments linear, 1.5–4 cm x 1–1.5(–2) mm (length:width ratio 15–40:1); basal basiscopic pinnule 1.8–3.5 cm long, 0–3-lobed, terminal segment 1–1.5(–2) mm wide; adaxial and abaxial surfaces glabrous, the veins prominent abaxially; laminar margin curved, strongly modified in 0.1–0.3 mm wide false indusia, deeply erose, nearly discontinuous, surface smooth or slightly white-papillate; spores black.
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Discussion
Allosorus angustifolius (Kunth) C. Presl, Suppl. Tent. Pterid. 152. 1836. Onychium angustifolium (Kunth) Kunze, Farrnkra¨uter 2: 11. 1848. Pellaea angustifolia (Kunth) Baker in Hooker & Baker, Syn. Fil. 150. 1867. Type. Mexico. [Michoaca´n:] “Crescit locis subapricis in monte ignivomo Jorullo, alt. 630 hexapl.” Humboldt & Bonpland s.n. (B-Willd. 20116!; P-Humb.!). Allosorus angustifolius (Kunth) C. Presl var. minor Liebm., Mexic. Bregn. 219 (reprint 67). 1849. Lectotype (chosen by Smith, 1981: 71). Mexico. Oaxaca: Yavesia, Liebmann s.n. [Pl. Mex. 2349, Fl. Mex. 231] (C!). Cheilanthes venusta Fe´e var. aurata Fe´e, Me´m. Foug. 9: 12. 1857, nom. nud., based on Mexico. [Oaxaca:] San Pedro de Nolasco, Galeotti 6560 (BR!-6 sheets).
Unverified, Doubtful, or Mistaken Reports. Ags (De la Cerda & Garci´a 971, HUAA, cited by Siqueiros-Delgado & Gonza´lez-Adame, 2004, but not verified).
The C. angustifolia complex, including also C. cuneata, C. decomposita, and C. chaerophylla, is in need of careful biosystematic study. The large, round, black spores found in all its members seem to indicate apogamy, and intermediate specimens exist between the species as characterized here. Our concepts of the four species have been carefully matched with the illustrations in Martens & Galeotti (1842) (for C. decomposita and C. chaerophylla), microfiche of the Willdenow herbarium (for C. angustifolia), and photo of type material at Berlin (for C. cuneata), as well as examination of the type specimens. Cheilanthes angustifolia and C. cuneata, as indicated in the key, have blades that are less divided (2–3-pinnate vs. 3–4-pinnate), more narrowly deltate (vs. broadly deltate), and fronds that are shorter than those of C. decomposita and C. chaerophylla. Cheilanthes angustifolia has long, narrow terminal pinna segments, a deltate blade, and deeply erose, narrow indusia (see key), whereas C. cuneata has wider, ovate, terminal pinna segments, ovate blades, more pinna pairs, and wider, suberose indusia. These two species seem to intergrade and may prove to be conspecific. Cheilanthes decomposita has long, narrow, conform terminal segments, and larger basal pinnae, whereas C. chaerophylla has shorter, ovate, pinnatifid terminal segments, and smaller basal pinnae. The status of the intermediate specimens is unclear, and the presence of globose spores and presumed apogamy in the whole group precludes using spore abortion as a test for hybridity. The intermediates between C. angustifolia and C. cuneata have fronds that are tripinnate (less divided and smaller than C. chaerophylla and C. decomposita), parallel-sided for the basal half (not ovate like C. cuneata and not deltate like C. angustifolia), conform terminal pinna segments that are 0.8–2.2 cm long, 1.5–3 mm wide (length:width ratio 5–14:1), and ascending pinnae. These intermediates (all at NY) are known from the states of Jalisco, Durango, Me´xico, Oaxaca, and Chiapas. The intermediates between C. cuneata and C. decomposita have blades that are tripinnate to tripinnate-pinnatifid, narrowly deltate, and have broad, conform terminal pinna segments. These are known from the states of Sinaloa, Nayarit, Veracruz, and Oaxaca. Intermediate specimens considered as hybrids by Mickel and Beitel (1988) are here merely designated as intermediates. There seem to be no sharp boundaries between the members of the complex.
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Distribution
Slopes in dry to moist oak or pine forests, on gravelly bluffs and limestone rocks; 100–2450 m. Mexico; Guat, Hond, Salv, Nic, CR, Pan.
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