Asplenium heterochroum Kunze

  • Authority

    Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.

  • Family

    Aspleniaceae

  • Scientific Name

    Asplenium heterochroum Kunze

  • Description

    Species Description - Roots thin to filamentous, wiry, not proliferous; rhizomes erect; rhizome scales bicolorous, center strongly clathrate, margins lighter, lumina not occluded, ca. 1.5 x 0.3–0.5 mm, entire; fronds numerous, clumped, (5–)8–15(–35) cm long; stipes black, lustrous, 1–4(–7) cm x 0.3–1 mm, 1/10–1/5 of frond length, with hair-like scales ca. 2 x 0.1–0.2 mm long, adaxially with tan wings 0.1–0.2 mm wide; blades thin-chartaceous, linear, 1-pinnate, 7– 12 cm x 7–18 mm, slightly narrowed proximally (sometimes nearly to the rhizomes), tapering at tips to confluent, sometimes ligulate terminal segments; rachises black, lustrous, glabrous, with tan wings ca. 0.1 mm wide on adaxial shoulders; pinnae oblong, 15–25(–45) pairs, 3–6 x 1.5–3(–4) mm, stalked to 0.2 mm, bases inequilateral, cuneate basiscopically, apices rounded to serrulate, acroscopic margins serrulate, sinuate-crenate, or subentire; veins simple to 1-forked, vein tips obscure adaxially; indument abaxially of whitish appressed clavate hairs 0.1 mm long; sori mostly 2–5 pairs per pinna, on both sides of midveins; indusia 0.5–1 x 0.3–0.5 mm, margins erose; spores reniform; 2n=144 (Fla).

  • Discussion

    Type. Cuba. Poeppig s.n. (LZ destroyed; isotypes BM!, NY!).

    Asplenium heterochroum is distinguishable from all the lustrous- and dark-stiped, 1-pinnate Aspleniums (except A. nesioticum, A. resiliens, and A. palmeri) by the lack of conspicuous hydathodes adaxially on the blades. The closest relative in Mexico, and perhaps elsewhere, is A. nesioticum, from which A. heterochroum differs by the thinner blade texture (veins readily visible by transmitted light) and more sharply crenate-dentate pinna margins (Maxon, 1913). The smaller, thinner, more dentate pinnae, more delicate, arching fronds without strongly deflexed pinnae, smaller rhizome scales (2 mm), and occurrence at lower elevations, distinguish A. heterochroum from A. resiliens (which see). The occurrence at lower elevations and lack of terminal buds on the blades distinguish A. heterochroum from A. palmeri (which see).

  • Distribution

    Epipetric on limestone rocks, or terrestrial in calcareous soils; 200–1400 m. USA (Fla); Mexico; Bel; Berm, Cuba, Hisp, PR; Col, Ven, Ec. Also reported from Guatemala by Stolze (1981), but the species is more broadly circumscribed in that work, with the inclusion of A. palmeri, regarded here as distinct; Adams (in Davidse et al., 1995), using the same circumscription adopted here, also cited a collection from Guatemala.

    Bermuda South America| México Mexico North America| Belize Central America| Florida United States of America North America| Cuba South America| West Indies| Puerto Rico South America| Venezuela South America| Ecuador South America| Guatemala Central America|