Diplazium expansum Willd.

• Authority

  Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.

• Family

  Athyriaceae

• Scientific Name

  Diplazium expansum Willd.

• Description

  Species Description - Rhizome erect; rhizome scales brown to black, clathrate with horizontal walls gone, leaving vertical wall latticework (scales retiform), 5-7(-15) mm long, 2-3 mm wide; fronds clumped; stipe 55-100 cm long, 1/3-½ the frond length, light brown, dark and scaly at base, glabrous; blade debate to ovate, bipinnate-pinnatifid, to 100 cm long, apex pinnatifid; adaxial rachial and costular groove with erect, minute (0.1 mm long) stubble, rachis and costae with dense to scattered erect, slightly twisted hairs (0.1-0.3 mm long); pinnae and pinnules equal, truncate; pinnae 2535 cm long, 10-13 cm wide, long-stalked (3-4.5 cm); pinnules cut ½-¾ of distance to midrib, short-stalked (1-2 mm) with rare scales at base (0.51 mm long); ultimate segments obtuse, crenulate to subentire; abaxial veins and lamina short-hairy (0.1-0.3 mm), upper surface glabrous, glossy; veins free, hydathodes prominent; indusia 3-5 mm long, 0.3-0.5 mm wide, erose.

• Discussion

  Asplenium expansum (Willdenow) Presl, Reliq. haenk. 1:46. 1825. Athyrium expansum (Willdenow) Milde, Bot. Zeitung (Berlin) 28: 353. 1870, nom. illeg., non Moore, 1860. Type. Venezuela. Caracas, Bredemeyer s.n. (B-Willd. 19948!). Among the bipinnate-pinnatifid taxa, the combination of retiform rhizome scales, minute puberulence in the rachial and costal grooves and equilateral pinnae distinguish Diplazium expansum, D. hellwigii and D. hians from the other taxa. The presence of long hairs on the rachises, costae, pinnule veins and lamina, the almost total lack of rachial and costular scales, and the erose indusia (0.3-0.5 mm wide) distinguish D. expansum from D. hellwigii, which has numerous rachial and costal scales, no hairs on abaxial rachis, costae, pinnule veins or laminar surface, and narrow, laciniate-ciliate indusia (uncut portion 0.1-0.3 mm wide). Diplazium hians also lacks the long, lax hairs on the rachis, costae, pinnule veins and laminar surface but has wider eróse indusia (0.3-0.5 mm wide) and narrow scales only on the lower surface of the pinnules. Diplazium expansum is similar to D. ingens Christ of Costa Rica, which is glabrous except for the minute puberulence in the rachial and costular grooves and a few minute hairs in the pinnule axes, and has narrow, ciliate indusia (uncut portion 0.1-0.3 mm wide).

• Distribution

  Mexico North America|