Cyatheaceae Kaulf.

Tree ferns. Rhizome erect [often referred to as the truck] or (not in Australia) prostrate, or rarely epiphytic on rainforest trees, with vascular tissue forming a hollow cylinder perforated by leaf gaps, appearing (in T.S.) to have meristeles; inner sides supported by very dense sclerenchyma; base of rhizome covered with interwoven adventitious roots. Stipes in a tight spiral at rhizome apex (except C. robertsiana); bases or entire stipe covered by scales; adaxial surface with short, stiff hairs; lateral pneumathodes forming discontinuous lines on stipe and rachis. Lamina 2-or 3-pinnate, or rarely (not in Australia) 1-pinnate; lower pinnae variously reduced, never with elongate, basiscopic pinnules; a small pneumathode present at the base of each pinna; rachis with hairy adaxial surface and a rarely hairy, but variously scaly, abaxial surface; scales progressively smaller distally and on costae of pinnules; pinnules ± deeply lobed, or sometimes pinnate; veins pinnate in pinnule lobes, always free. Sori indusiate or exindusiate, on or near the veins, paraphysate; indusium either attached all around base of receptacle and covering young sorus, opening to form a firm-edged cup or opening by irregular rupture, or attached only on costular side of receptacle (hemitelioid condition) and of varying size, in some cases quite hidden by mature sorus; exindusiate species may have overlapping scales around base of receptacle, either covered by, or ± covering the sporangia; receptacle swollen; sporangia almost sessile, narrower towards base, with a complete, oblique annulus. Spores trilete, 16, 32 or 64 per sporangium; perispore spinulose or with radial ridges.