Hymenophyllopsidaceae

Abstract

Small, delicate, epilithic or terrestrial ferns with short-to long-creeping, solenostelic, non-sclerotic stem clothed with stramineous to dark brown, non-peltate, non-clathrate, long and narrow, entire or denticulate scales. Petioles spirally arranged, close, non-articulate, sulcate, bisulcate, or terete, scaly at base (or villous in H. superba Lellinger), with two vascular bundles that coalesce upward. Lamina hairy when young, pinnate + pinnatifid to 3-pinnate + pinnatifid, anadromous, free-veined, sometimes scaly like the petiole-base (villous in H. superba), of c. 3 or 4 layers of cells, only the epidermis chlorophyllous; stomata wanting. Ultimate segments often dichotomous, uninerval. Sori terminal on a vein (but the veins often bearing branches flanking the sorus), subterminal on their segment; receptacle short. Indusium attached at the base and part of the sides, short, anatomically like the lamina, forming a kind of pouch with the lamina lobe opposite it, this of about the same length, entire, lobed, or deeply lacerate. Sporangia few, intermingled with some hairs; pedicel short, pluriseriate; capsule large, very asymmetric, with somewhat oblique annulus running past the insertion and interrupted by the well-differentiated, pluricellular stomium. Spores globose, trilete, granulate, non-chlorophyllous. Gametophyte and karyology undescribed.