Diplazium expansum Willd.

  • Authority

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

  • Family

    Athyriaceae

  • Scientific Name

    Diplazium expansum Willd.

  • Description

    Species Description - Rhizomes erect; rhizome scales brown to black, clathrate with horizontal walls gone, leaving side-wall latticework (scales retiform), 5–7(–15) x 2–3 mm; fronds 100–200(–300) cm long; stipes tan except for darkened bases, 55–100 cm long, 1/3–1/2 the frond length, scaly at bases, glabrous or glabrescent distally; blades thick-herbaceous to chartaceous, 2-pinnate-pinnatifid, to 100 cm long, deltate to ovate, apices pinnatifid, lacking buds; rachises with often numerous hairs 0.1–0.4 mm, lacking papillae in adaxial grooves; pinnae stalked 1–4.5 cm, equilateral, (17–)25–35 x 8–13 cm, pinnules sessile to stalked 1–2 mm, equilateral, cut 1/2– 3/4 of distance to costules, lobes obtuse, crenulate to subentire, costae and costules adaxially winged perpendicular to the plane of the blades; indument adaxially of hairs 0.1 mm long in rachial, costal, and costular grooves, abaxially with scattered tan linearlanceolate scales along costae and costules, scales 0.5–2 mm long, the blades also with usually moderate to dense, often septate hairs 0.1–0.3 mm long on costae, costules, veins, and laminae between veins; veins free, pinnate, 4–8 pairs in ultimate segments, simple or 1-forked; sori pinnate on ultimate segments, with erose indusia 3–5 x 0.3–0.5 mm; 2n=ca. 328 (Jam).

  • Discussion

    Asplenium expansum (Willd.) C. Presl, Reliq. Haenk. 1(1): 46. 1825. Athyrium expansum (Willd.) Milde, Bot. Zeitung (Berlin) 28: 353. 1870, hom. illeg., non T. Moore, 1860. Type. Venezuela. Caracas, Bredemeyer s.n. (B-Willd. 19948!).

    Among the 2-pinnate-pinnatifid taxa, the combination of retiform rhizome scales, minute hairs in the rachial and costal grooves, and equilateral pinnae distinguish D. expansum, D. hellwigii, and D. hians from the other taxa. The presence of hairs on the rachises, costae, veins and laminae between veins, the paucity of rachial and costal scales, and erose indusia 0.3–0.5 mm wide distinguish D. expansum from D. hellwigii, which has numerous rachial and costal scales, no hairs on rachises, costae, veins, or tissue between veins abaxially, and narrower, laciniateciliate indusia (uncut portion 0.1–0.3 mm wide). Occasional specimens of D. expansum have more numerous costal scales and rather sparse laminar hairs. Diplazium hians also lacks hairs on the rachises, costae, veins, and tissue between veins abaxially, but has erose indusia 0.3–0.5 mm wide and narrow scales on the costae and costules abaxially. Diplazium expansum is similar to D. ingens Christ of Costa Rica, which is glabrous except for a few minute hairs on the costules and hairs in the rachial and costal grooves adaxially; that species also has narrower, ciliate indusia (uncut portion 0.1–0.3 mm wide).

  • Distribution

    Terrestrial in montane rain forests; (100–)800– 1650(–2600) m. Mexico; Guat, CR; Gr Ant; Col, Ven, Ec, Peru, s Braz, Bol. Adams (in Davidse et al., 1995) also cited a collection from Nicaragua. Proctor (1977) reported the species from St. Vincent, but this may be based on a misidentification of D. striatum (e.g., Morton 5469, UC).

    Nicaragua Central America| Bolivia South America| Brazil South America| Peru South America| Ecuador South America| Venezuela South America| Costa Rica South America| Guatemala Central America| México Mexico North America|