Plagiogyriaceae

Abstract

Terrestrial, medium-sized ferns with creeping or more often erect, mostly unbranched, dictyostelic stem without scales or hairs. Leaves close, spirally arranged; petiole non-articulate, well-developed, expanded at base, bearing two rows of knob-like aerophores on the expansions, with a single vascular bundle that is U- or V-shaped in cross-section, or with 3 bundles merging above into one, in section quadrangular, trigonous, or rarely terete. Lamina (and petiole above the base) when young densely covered with pluricellular hairs with swollen, glandular, mucilage-secreting end cell, later glabrescent, pinnatifid or simply pinnate, dimorphic; rachis adaxially sulcate, often with lateral flanges or wings; aerophores like those on the petiole base present on the lamina of croziers, sometimes extending all the way from petiole to leaf tip. Sterile pinnae sessile or adnate, rarely short-stalked, long and narrow, herbaceous to coriaceous, serrate-dentate at least near the apex; costa convex above. Upper pinnae of sterile and fertile leaves reduced and confluent, or a subconform terminal pinna present. Stomata anomocytic. Veins simple or forked, free, with slightly enlarged ends very near the margin, in the teeth, if any. Fertile leaves stiffly erect, their pinnae very narrow, linear; veins sometimes somewhat anastomosing towards their ends. Sporangia borne on the enlarged distal parts of the veins, seemingly acrostichoid at full maturity; indusium and sterile appendages among the sporangia none but the young sporangia covered by the somewhat reflexed leaf margin; stalk long, c. 6-seriate; capsule asymmetric, with complete, slightly oblique annulus, the greater part thickened, the bow interrupted by a several-celled stomium near the stalk, dehiscence transverse. Spores trilete, tetrahedral, depressed between the angles; outer layer of bistratose perispore forming rodlets; surface bearing coarse tubercles with papillae and rodlets.