Page:Manual of the New Zealand Flora.djvu/982

942

Ferns, usually of small size. Rhizome slender or rather stout, often much branched, glabrous or tomentose. Fronds compound or rarely simple and entire, of the same delicately membranous texture as Hymenophyllum, often pellucid, usually of a single layer of cells, rarely of 3–6 layers. Ultimate segments linear or narrow-oblong, entire or rarely toothed at the margin, with a stout central costa. Sori marginal, terminal or lateral, more or less immersed in the frond or quite free, always terminating a vein. Indusium tubular or trumpet-shaped, truncate at the mouth or with a narrow spreading lip or border, usually of the same texture as the frond. Receptacle elongated, filiform or columnar, usually exserted beyond the indusium. Sporangia sessile, depressed, surrounded by a broad complete horizontal ring, bursting transversely.