Cheiropleuriaceae

Abstract

Terrestrial or epilithic ferns of medium size with creeping, protostelic, rarely branching stem covered with long, uniseriate, articulate hairs. Petioles more or less close, hairy at the base only, non-articulate, several-ranked, terete, upward gradually flattened and marginate, with two vascular strands at base which divide upward. Lamina naked, strongly dimorphic; sterile lamina firmly herbaceous, more or less deeply bilobed or not rarely simple, rarely 4-lobed, hypostomatic, the main veins dichotomously forking with anadromous branching, the smaller veins areolate with smaller areoles included in the larger ones and numerous free included ultimate veinlets, all veins more or less prominent; stomata paracytic. Fertile lamina simple, long, and narrow, with three longitudinal main veins, abaxially almost wholly covered by the sporangia, these served by special branches of the veins running to near the surface. Sporangia of mixed maturation, intermingled with hairs with swollen terminal cell; stalk short, massive, quadriseriate, constricted below the head; head with almost vertical yet uninterrupted annulus largely consisting of the bow, with well-differentiated stomium. Spores, achlorophyllous, c. 128 per sporangium, trilete, tetrahedral, with prominent ridge near the aperture; surface smooth to rugulose.