Nephrolepidaceae

Abstract

Terrestrial, epilithic, or epiphytic ferns; stem erect or short-creeping, rarely elongate, with a radial dictyostele, bearing peltate scales with few-celled marginal hairs, projecting teeth, and caducous superficial hairs. Protostelic runners often present, their stele turning into a dictyostele as they form adventitious buds; in a few species they also bear tubers. Petioles close, non-articulate, sometimes very short, with two larger ventral and a few smaller dorsal bundles arranged in a U-shape, adaxial side flattened to sulcate, not dark-sclerotic, without pneumatophores, sometimes persistently hairy and/or scaly. Lamina long and narrow, simply pinnate, with numerous, often close pinnae, the apex maturing slowly, pinnatifid; rachis like the petiole, adaxially grooved. Pinnae sessile, articulate at base, inserted on the ridges bordering the rachis groove, often lanceolate, with adaxially grooved, sometimes scaly and/or hairy, percurrent costa; base of pinnae unequal, the anterior side often auricled. Fertile pinnae occasionally somewhat difform, more incised and/or narrower than the sterile pinnae. Veins free, simple or forked, or pinnate in the basal auricle; venation ± isodromous. Vein ends bearing hydathodes behind the margin; pinna margin entire, or lobed to pinnatifid to the middle. Stomata polocytic or monocyclic-staurocytic. Surface of pinnae sometimes persistently hairy. Basal pinnae not rarely reduced; upper part of lamina very gradually narrowed to the tip. Sori terminal on acroscopic branches of veins (groups), medial to submarginal, usually round or oval-reniform, sometimes placed in the lobes near their apices, in one species linear and occupying many vein ends. Indusium reniform to suborbicular-subpeltate, linear in one species; no sterile appendages among the sporangia. Spores monolete, ellipsoidal or spheroidal, surface irregularly low-tuberculate to rugose, sometimes with spherical deposit.