Blechnum

• Authority

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

• Family

  Blechnaceae

• Scientific Name

  Blechnum

• Description

  Genus Description - Terrestrial, hemiepiphytic or epiphytic; rhizome long-creeping to compact and erect, rarely forming a trunk, scaly, often stoloniferous and forming large stands; fronds small to medium-sized (to large); stipe stramineous to atropurpureous, glabrous to sparsely scaly, nonarticulate to rhizome; fronds mostly pinnatifid to pinnate, rarely undivided, margin entire to serrulate, young fronds usually reddish; fronds monomorphic or dimorphic; lamina glabrous, occasionally with small scales on midveins, thin to coriaceous; veins free, parallel, going to or nearly to margin; sori costal, on commissural veins parallel to costae connecting adjacent veins, indusiate; indusia opening toward costa, entire to laciniate; spores bilateral, nearly smooth, perispore inconspicuous to winged.

• Discussion

  Lectotype (chosen by J. Smith, Hist. fil. 300. 1875): Blechnum occidentale Linnaeus. Struthiopteris Weis, Pl. crypt, fl. gott. 286. 1770. Type: Struthiopteris spicant (Linnaeus) Weis [=Osmunda spicant Linnaeus; =Blechnum spicant (Linnaeus) J. E. Smith]. Lomaria Willdenow, Berlin. Mag. 3: 160. 1809. Type: Lomaría nuda (Labillardière) Willdenow [=Onoclea nuda Labillardière, = Blechnum nudum (Labillardière) Luerssen]. For additional synonymy, see Tryon and Tryon (1982). The nearly 200 species are primarily tropical, with one boreal-temperate species and several austral-temperate. There are about 15 species in Mexico, with 13 in Oaxaca; most are widespread, extending into Central and South America. The genus has sometimes been divided on the basis of monomorphic (Blechnum) vs. dimorphic fronds {Lomaría), but there are several groupings of dimorphic-fronded species, each of which could conceivably be considered a distinct genus: sect. Lomariocycas (J. Smith) Morton with stout trunks (Bolivia to Costa Rica [not in Mexico]); sect. Parablechnum (Presl) Moore with stout, short, erect rhizomes (e.g., B. schiedeanum, and perhaps not including B. spicant); sect. Lomaría (Willdenow) Keyserling with erect, slender trunks and reduced basal leaflets (e.g., B. divergens); and sect. Lomaridium (Presl) Mickel & Beitel (basionym: Lomaridium Presl, Epimel. bot. 154. 1851) with climbing rhizomes and toothed rhizome scales (e.g., B. fragile). The monomorphic species seem closely allied except for B. serrulatum in sect. Diafnia (Presl) J. Smith. The Oaxacan species of Blechnum can be characterized by adaxially grooved stipes, the grooves extending through the costae, except as noted. With the exception of B. serrulatum, there are enlarged vein endings, which are visible adaxially, except in B. fragile and B. ensiforme, in which the vein endings are visible on the lower surface. References: Broadhurst, J. 1912. The genus Struthiopteris and its representatives in North America. Bull. Torrey Bot. Club 39: 257-278, 357-385; Morton, C. V. & D. B. Lellinger. 1967. Notes on the ferns of Dominica and St. Vincent. Amer. Fern J. 57: 66-77; Murillo, M. T. 1968. Blechnum subgénero Blechnum en Sur América, con especial referencia a las especies de Colombia. Nova Hedwigia 16: 329-366; Walker, T. G. 1966. A cytotaxonomic survey of the pteridophytes of Jamaica. Trans. Roy. Soc. Edinburgh 66: 169-237; Walker, T. G. 1973. Additional cytotaxonomic notes on the pteridophytes of Jamaica. Trans. Roy. Soc. Edinburgh 69: 109-135; Walker, T. G. 1985. The cytology and taxonomic implications. In A. C. Jermy & T. G. Walker, Cytotaxonomic studies of the ferns of Trinidad. Bull. Brit. Mus. (Nat. Hist.), Bot. 13: 133-276.