Range

Plants terrestrial, epilithic or epiphytic. Rhizome short to wide-creeping, or erect to suberect, simple or branched, closely set with roots, persistent stipe bases and scales, scales thinly chartaceus, chartaceus or crustaceous, clathrate, sessile or adnate, entire or variously set with outgrowths, apex terminates in a thin-walled cell. Fronds monomorphic, crowded and caespitose or closely to widely spaced, erect, suberect, or arching; stipe generally with two distinct vascular bundles uniting upwards into a single X-shaped bundle, firm, terete, adaxially sulcate, or the sulcus centrally raised, often narrowly green-winged for most of the length, or in the upper half, variously set with glands, hairs and scales, hairs 3 to 4-celled, scales chartaceus, clathrate, sessile, cordate to cordate-imbricate, entire or variously set with outgrowths, apex terminates in a thin-walled cell; lamina anadromous, herbaceous to firmly herbaceous, or coriaceus, 1 to 3-pinnate, with up to 36 petiolated pinna pairs, often with a proliferous bud adaxially on the rachis near the apex, or at the apex of a rachis extension; rachis and lower order axes firm, terete, sulcate, or sulcus centrally ridged, adaxially, often narrowly green-winged, variously set with glands and scales similar to, but smaller than, those on the stipe. Stomata usually of the anomocytic and copolocytic types, hypostomatic. Venation anadromous, free, obscure or evident, often raised adaxially, flabellately forked, or pinnately branched, ending near the margin. Sori linear, extending along a vein, inframedial, medial, or supramedial, at, below, or above a vein fork, or cupuliform and then borne terminally on each lobe, acentric; receptacle nude or with simple, pluricellular, hair-like paraphyses, apical cell acicular; indusium membranous, herbaceous, or chartaceus, linear or semicircular, entire or lacerate, attached along the entire length; sporangium long-stalked, simple, uniseriate, 3-seriate below the capsule, capsule globose in lateral view, with (16-)18, 19, 21, 23(-27) indurated annulus cells, epistomium (1-)2, 3(-3)-celled, hypostomium (3-)4, 6(-7)-celled. Spores 32 or 64 per sporangium, elliptic to broadly elliptic, monolete, with low, narrow or broad reticulate ridges and prominent wings, often laciniate or erose, the areas between the wings often irregularly echinulate, or with a fine reticulate meshwork, exospore 28-60 x 16-56 (m. Chromosome number 2n = 72, 144 or 288, sexual or apogamous. Asplenium is often subdivided into several smaller genera and subgenera. Morton & Lellinger (1966) recognize Loxoscape T.Moore and placed the species with veins and sori occurring at an acute angle to the costa, and with rachises more or less scaly and sometimes hairy in Asplenium section Sphenopteris Mett. The occurrence of intermediate forms between these genera and sections render most of these classifications unsatisfactory. The classification followed here is conservative in that only two subgenera, Asplenium and Ceterach Willd. are recognized. Asplenium section Hymenasplenium (Hayata) K.Iwats. is widely accepted as a well-defined group (Mitui et al. 1989; Murakami & Moran 1993). The section is defined by creeping rhizomes, dorsiventrally symmetrical steles, swollen stipe bases or trophopods, and chromosome numbers based on n = 38 or 39. Asplenium unilaterale Lam. belongs to this section.

Range

Plants terrestrial, epilithic or epiphytic. Rhizome short to wide-creeping, or erect to suberect, simple or branched, closely set with roots, persistent stipe bases and scales, scales thinly chartaceus, chartaceus or crustaceous, clathrate, sessile or adnate, entire or variously set with outgrowths, apex terminates in a thin-walled cell. Fronds monomorphic, crowded and caespitose or closely to widely spaced, erect, suberect, or arching; stipe generally with two distinct vascular bundles uniting upwards into a single X-shaped bundle, firm, terete, adaxially sulcate, or the sulcus centrally raised, often narrowly green-winged for most of the length, or in the upper half, variously set with glands, hairs and scales, hairs 3 to 4-celled, scales chartaceus, clathrate, sessile, cordate to cordate-imbricate, entire or variously set with outgrowths, apex terminates in a thin-walled cell; lamina anadromous, herbaceous to firmly herbaceous, or coriaceus, 1 to 3-pinnate, with up to 36 petiolated pinna pairs, often with a proliferous bud adaxially on the rachis near the apex, or at the apex of a rachis extension; rachis and lower order axes firm, terete, sulcate, or sulcus centrally ridged, adaxially, often narrowly green-winged, variously set with glands and scales similar to, but smaller than, those on the stipe. Stomata usually of the anomocytic and copolocytic types, hypostomatic. Venation anadromous, free, obscure or evident, often raised adaxially, flabellately forked, or pinnately branched, ending near the margin. Sori linear, extending along a vein, inframedial, medial, or supramedial, at, below, or above a vein fork, or cupuliform and then borne terminally on each lobe, acentric; receptacle nude or with simple, pluricellular, hair-like paraphyses, apical cell acicular; indusium membranous, herbaceous, or chartaceus, linear or semicircular, entire or lacerate, attached along the entire length; sporangium long-stalked, simple, uniseriate, 3-seriate below the capsule, capsule globose in lateral view, with (16-)18, 19, 21, 23(-27) indurated annulus cells, epistomium (1-)2, 3(-3)-celled, hypostomium (3-)4, 6(-7)-celled. Spores 32 or 64 per sporangium, elliptic to broadly elliptic, monolete, with low, narrow or broad reticulate ridges and prominent wings, often laciniate or erose, the areas between the wings often irregularly echinulate, or with a fine reticulate meshwork, exospore 28-60 x 16-56 (m. Chromosome number 2n = 72, 144 or 288, sexual or apogamous. Asplenium is often subdivided into several smaller genera and subgenera. Morton & Lellinger (1966) recognize Loxoscape T.Moore and placed the species with veins and sori occurring at an acute angle to the costa, and with rachises more or less scaly and sometimes hairy in Asplenium section Sphenopteris Mett. The occurrence of intermediate forms between these genera and sections render most of these classifications unsatisfactory. The classification followed here is conservative in that only two subgenera, Asplenium and Ceterach Willd. are recognized. Asplenium section Hymenasplenium (Hayata) K.Iwats. is widely accepted as a well-defined group (Mitui et al. 1989; Murakami & Moran 1993). The section is defined by creeping rhizomes, dorsiventrally symmetrical steles, swollen stipe bases or trophopods, and chromosome numbers based on n = 38 or 39. Asplenium unilaterale Lam. belongs to this section.