Adiantum petiolatum Desv.
Descripción
Rhizomes short-creeping, 2–4 mm diam.; rhizome scales castaneous, entire to faintly denticulate, linear-lanceolate, 2.5–3 X 0.5 mm; fronds distant, mostly 2–5 mm apart, 22–45 cm long, arching; stipes black, lustrous, 10–25 cm X 1–1.5 mm, ca. 1⁄2–2⁄3 the frond length, glabrous or with sparse pectinate scales to 2 mm long; blades oblong-deltate, 1-pinnate; rachises atropurpureous, with scattered scales and hairs, glabrescent, the scales linear, branched or pectinate at the bases, otherwise entire or nearly so; pinnae 6–9 pairs, the proximal pinnae often largest, 3.5–6.5 cm long, distal pinnae 1⁄2–3⁄4 as long, lateral pinnae inequilateral, stalked 1–5 mm, stalk color passing into pinna bases, terminal pinna subconform, equilateral, pinna bases oblique, margins finely and evenly serrulate, apices acute or acuminate, costae near mid-pinna or slightly closer to basiscopic margins, nonarticulate; veins free, forking, ending in marginal teeth; indument absent on both surfaces; idioblasts present on both blade surfaces, conspicuous adaxially, sometimes faint abaxially; sori 6–14 along acroscopic margins, also to 9 along distal part of basiscopic margins; indusia 1–6 mm long, oblong, linear, or slightly arcuate, glabrous; 2n=60 (Braz).A
Forma de vida
TerrestreA
Ejemplar revisado
Chis (Breedlove 49150, 56781, CAS; Ventura & López 2110, ENCB, NY). Oax (Mickel 4184, MEXU, NY, UC, 5175, 5832, 6834, NY, UC). Tab (Matuda 3336, NY). Ver (Martínez C. 1035, ENCB, MEXU, XAL; Orcutt 3201, DS, MEXU, NY, US).A
Elevación
100 – 600 mA
Ecología y Hábitat
Along shaded wet streams banks.A
Tipo de vegetación
Selva alta, Selva medianaA
Categoría IUCN
No incluidaB
Categoría NOM-059-SEMARNAT-2010
No incluidaC
Discusión taxonómica
All specimens here cited from Oaxaca were identified as A. Obliquum by Mickel and Beitel (1988). However, we now believe that they are more properly assigned to A. petiolatum because of their simply and finely serrulate pinna margins, glaucous abaxial blade surfaces, and relatively sparsely scaly rachises. Specimens agreeing with the Mexican ones are relatively common in Mesoamerica. Adiantum obliquum differs in having doubly and more coarsely serrate pinna margins, green blade surfaces, scalier blade surfaces abaxially, and denser rachis scales. The character of the idioblasts used by Moran et al. (in Davidse et al., 1995), conspicuous on both sides in A. obliquum, but conspicuous on the adaxial side only in A. petiolatum, while perhaps a tendency, does not seem to be definitive. Adiantum latifolium is also very closely related, differing primarily in being bipinnate, rather than simply pinnate.A