The World Flora Online

Plants terrestrial, herbaceous, frequently in clumps. Stems creeping, beset with old petiole bases and black fibrous roots; scales absent; older stems seldom persisting. Leaves monomorphic or dimorphic. Blades 1--2-pinnate (2-pinnatifid); rachises grooved. Pinnae monomorphic or dimorphic. Indument of reddish to light brown hairs. Veins dichotomous, running to margins. Sori absent; sporangia born on slightly modified fertile segments of blades also possessing fully expanded pinnae, or sporangia covering blades lacking green expanded pinnae, clustered in marginal zones, indusia lacking. Spores green, all alike. Gametophytes green, aboveground, obcordate to elongate.

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Plants terrestrial, with mostly unbranched, often massive, erect, or shortly creeping, ascending, sometimes treelike trunk clothed in roots and persistent stipes, hairy at apex. Rhizome anatomy distinctive, an ectophloic siphonostele (with a pith of parenchyma in center and phloem outside of vascular cylinder only), with a ring of discrete xylem strands, these often conduplicate or twice conduplicate in cross section. Fronds 1- or 2-pinnate, catadromous, when young bearing wool-like, uniseriate hairs, these deciduous or persistent at axes, dimorphic or with fertile portions dissimilar to sterile; stipe caespitose, spirally arranged, with laterally winged stipules at bases, bearing mucilaginous hairs when young, with a single U-shaped vascular bundle; sclerenchyma strongly developed; base of lateral pinnae nearly always distinctly articulate (but only functional in some species); pinnule base sometimes also articulate, though less distinctly so; veins free, subpinnately furcate. Sporangia not assembled in sori, following veins or entirely covering strongly contracted fertile segments, sporangia large, with 128-512 spores, opening by an apical slit, annulus lateral; spores green, subglobose, trilete; gametophytes large, green, cordate, surficial. x = 22.

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Terrestrial ferns with suberect rhizomes, clothed with persistent leaf–bases; fronds bipinnate (in W.African species), spirally arranged, when young covered with long simple hairs, base with a stipule–like flange; leaf trace crescent–shaped; sporangia with walls one cell thick borne on both surfaces of fertile pinnules in the upper part of the leaves (in W.African species) pyriform with a short stalk made up of about 5 rows of cells; annulus represented by a cluster of lateral cells with thickened walls

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Terrestrial plants with erect or procumbent creeping rhizomes enclosed by a mass of persistent stipe-bases which are winged at the base

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Terrestrial plants with erect or procumbent creeping rhizomes enclosed by a mass of persistent stipe-bases which are winged at the base

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Fougères terrestres.\n\t\t\t\n\t\t\t\t Sporophytes'vivaces; rhizome dressé, entouré par la masse des bases pétiolaires persistantes.'Feuilles'à préfoliaison circinée, bi- ou tripennées, souvent recouvertes de poils simples pendant le développement, glabres à maturité.'Sporanges grands, localisés sur des divisions fertiles, non réunis en sores définis, à maturation simultanée; anneau de déhiscence apical, rudimentaire et constitué de quelques cellules épaissies.\n\t\t\t\n\t\t\t\t Spores toutes semblables, pourvues de chlorophylle.\n\t\t\tGamétophytes vivaces, épigés, cordés ou allongés, épais, vert foncé, avec une nervure centrale à la face inférieure.\n\t\t\tNombre chromosomique de base: x = 22.\n\t\t\tFamille subcosmopolite, groupant pour la plupart des auteurs trois genres,'Osmunda'L.,'Todea'Willd. et'Leptopteris'C. Presl, et une trentaine d'espèces. A. E. Bobrov [The Family'Osmundaceae , its taxonomy and geography, Bot. Journ. U.S.S.R., 52 : 1600-1610, 3 fig. (1967)] distingue en outre les genres'Osmundastrum'C. Presl et'Plenazium C. Presl, et reconnaît 36 espèces.\n\t\t\tSeul le genre'Osmunda est représenté en Afrique centrale.

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SELECTED REFERENCES

Bobrov, A.E. 1967. The family Osmundaceae (R.Br.) Kaulf. Its taxonomy and geography. Bot. Zhurn. (Moscow & Leningrad) 52: 1600--1610. Hewitson,W. 1962. Comparative morphology of the Osmundaceae. Ann. Missouri Bot. Gard. 49: 57--93.

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