Metaxyaceae

Abstract

Stem creeping-ascending, short, stout, dorsiventral, solenostelic, clothed with long, pluricellular, pointed, tawny trichomes. Petioles rather close, inserted laterally and dorsally on the stem, long, stout, brown, subterete, adaxially grooved, with long lateral pneumathodes; vascular bundle one, horseshoe-shaped and corrugated in transection; petiole base sometimes with adventitious buds, hairy, glabrescent. Rachis like the petiole, glabresecent, adaxially grooved, the groove not or only incompletely continuous with that of the costae. Lamina rather large, simply pinnate with conform terminal pinna; lateral pinnae alternate, short-stalked to subsessile, very elongate-oblong, subglabrous when mature, chartaceous-subcoriaceous, crenate-serrate towards the caudate-acuminate apex. Costa percurrent, adaxially sulcate; lower pinna bases anadromous, upper ones ± distinctly catadromous. Veins evident, close, free, simple or forked near the base, occasionally the two branches fusing outwards, ends clavate at the sclerotic margin. Sod dorsal on the veins, irregularly arranged, often near the costa but also extending towards the middle, sometimes two or even three sod borne on the same vein (unique in recent ferns), orbicular to elliptic; receptacle densely covered with filiform, several-celled, sometimes branched trichomes. Sporangia numerous, maturing together, with a short, 4-seriate stalk and large capsule; annulus nearly vertical, just bypassing the stalk, with distinct, several-celled stomium. Spores 64, trilete, globose; exospore of 2 layers; perispore thick, 3-layered, the outer layer forming a granulate deposit.