Adiantum raddianum C.Presl

  • Authority

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

  • Family

    Pteridaceae

  • Scientific Name

    Adiantum raddianum C.Presl

  • Description

    Species Description - Rhizomes short-creeping, 3–5 mm diam.; rhizome scales dark to light brown, linear-lanceolate, entire, 2.5–3 x 0.5 mm; fronds clumped, ca. 20–45 cm long, laxly arching; stipes dark reddish brown, 10–20 cm x 1–2 mm, ca. 1/2 the frond length, glabrous except at bases; blades ovate-deltate to ovate-lanceolate, 2–3- pinnate proximally, 1–2-pinnate distally, tapering to apices; rachises red-brown, glabrous; pinnae 6–9 pairs, pinnae and pinnules with stalks 1–5 mm long; pinnulets obovate to rhomboid, 8–12 mm long, sterile margins dentate, the stalk color passing into pinnulet bases, non-articulate; veins free, forking, ending in sinuses; indument absent on both surfaces; idioblasts absent; sori 4–6 per pinnulet, confined to distal margins; indusia 1–1.5 mm long, reniform to round-reniform, glabrous.

  • Discussion

    Type. Based on Raddi, Pl. Bras. Nov. Gen., t. 78, f. 2. 1825.

    Adiantum cuneatum Langsd. & Fisch., Pl. Voy. Russes Monde 1: 23. 1810 (t. 26, 1818), hom. illeg., non G. Forst., 1786. Type. Brazil. Santa Catharina Island, Langsdorff s.n. (LE! photo GH; isotypes B-Willd. 20096!, microfiche UC!, BM). Adiantum mexicanum C. Presl, Suppl. Tent. Pterid. 158. 1836. Presl cited only Adiantum cuneatum Schltdl., which is an indirect reference to a specimen (Schiede & Deppe “797”) cited by Schlechtendal in Linnaea 5: 615 (1930), without further description. The Schiede & Deppe collection (frag. NY!) is A. andicola. But because A. mexicanum has no description of its own, it must be regarded as an illegitimate renaming of A. cuneatum, which is here and by others treated as a synonym of A. raddianum. For additional synonymy, see Lellinger (1989: 153-154). Because of the spottiness and recency of collections of this species in Mexico, we suspect that A. raddianum may not be native, but rather recently introduced; dates of collection, where known, are given in the specimen citations, and all but one of the Mexican collections were made since 1966. Proctor (1985) discussed the possible naturalization of A. raddianum in Jamaica. It is certainly widely cultivated throughout the world, including Mexico, and it would be surprising if it had not escaped. However, nowhere, except possibly in the state of Morelos, does it seem to be common. Adiantum raddianum is closely related to A. poiretii, which see for distinguishing characters. The Fisher collection cited from Veracruz is immature and lacks rhizome, but it appears to belong to this species (although not matching other Mexican specimens very well); we wonder if it is a horticultural variant of A. raddianum.

  • Distribution

    Terrestrial on open or lightly shaded banks, oak forests, seasonal evergreen forests; 800–2200 m. Mexico; Guat, Nic, CR; Gr & L Ant; Col, Ven, Trin, Ec, Peru, Braz, Bol, Parag, Arg, Uru; widely naturalized in OW tropics.

    Mexico North America| Uruguay South America| Argentina South America| Paraguay South America| Bolivia South America| Brazil South America| Peru South America| Ecuador South America| Trinidad and Tobago South America| Venezuela South America| Colombia South America| West Indies| Costa Rica South America| Nicaragua Central America| Guatemala Central America|