Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.
Gleicheniaceae
Genus Description - Terrestrial; rhizomes long-creeping, cord-like, often ca. 2–3 mm diam., protostelic, bearing peltately attached lanceolate brown to castaneous scales, often glabrescent proximally; fronds erect or scandent, monomorphic, often to several meters long; blades pseudodichotomous, with pinnae consistently and repeatedly ±equally forking, ending in forking pinnatifid laminar parts, the frond apices often becoming dormant; dormant buds concealed by lanceolate, often fringed scales, the proximal one (or several), especially on the main axis, often also with a pair of stipules; accessory pinnae lacking at the branching points of fronds; penultimate divisions pectinate, bearing narrowly lanceolate to linear segments; indument abaxially, and sometimes adaxially, of sparse to numerous scales and/or branched or arachnoid hairs; veins free, generally once-forked; sori abaxial, 3–6 per sorus; sporangia globose to pear-shaped, with oblique annuli; paraphyses absent or filamentous; indusia absent; spores ellipsoid, with perispores laevigate, faintly rugulate or minutely perforate; x=34.
Lectotype (chosen by Christensen, Index Filic. LIV. 1906): Sticherus laevigatus laevigatus (Willd.) C. Presl [= Mertensia laevigata Willd.] = Sticherus truncatus (Willd.) Nakai.
Sticherus is subsumed in the genus Gleichenia by some authors, but in this treatment we restrict the use of the latter to only those species having bead-like segments (e.g., G. circinnata Sw.) in Australasia to southern Africa; Gleichenia s.str. comprises about 10 species. Sticherus is thought to comprise about 90 species, with about 40 in tropical America.
Sticherus is distinguished from Dicranopteris and Gleichenella by having veins 1-forked and by having scaly (vs. hairy) rhizomes. Affinities of Sticherus are clearly with the other gleichenioid fern genera, including also Gleichenia, Stromatopteris, and Diplopterygium (Hasebe et al., 1995; Pryer et al., 2003).
In a recent unpublished thesis, Gonzalez (2003) has revised the taxonomy of New World Sticherus. Using her species concepts, the names of three of the four Mexican species will change. These name changes are not adopted herein but are discussed under the individual species that are affected.