Sporangia large and rather stouter than those of other Leptosporangiate ferns, borne in small groups (filmy species of Todea) in linear and frequently confluent sori (Todea barbara; [fig. 221], D) or clustered round the axis of modified fertile pinnae with much reduced lamina (Osmunda). The annulus is represented by a group of thicker-walled cells a short distance below the apex ([fig. 221], C). This family stands apart among the ferns; in some respects, e.g. in the more robust sporangia occasionally forming synangia, and in the presence of stipular wings, it forms a transitional series between the Leptosporangiate and Eusporangiate ferns. The only European species of Osmunda, O. regalis, is almost cosmopolitan in range; other species occur in North and South America, in the Far East, the Malay Peninsula, and in other regions, more especially in the temperate zones. Todea is represented by (i) the South African and Australian species, T. barbara, a fern with a stem, which may reach a height of several feet, thickly covered with adventitious roots and bearing large and somewhat leathery fronds; (ii) filmy species in New Zealand, New South Wales, New Caledonia, and elsewhere. A plant of the small tree-fern Todea Wilkesiana (Fiji, Samoa, and other islands) in the filmy-fern house at Kew, to which my attention was drawn by my friend Mr A. W. Hill, has a slender stem with the characteristic leaf-scars exposed; it presents a striking similarity to some of the fossil species of Osmundaceae described in a later chapter.

Fig. 221.

  1. Osmunda cinnamomea (after Faull).
  2. Todea barbara, p, phloem; s, sclerenchyma.
  3. Osmunda regalis (after Luerssen).
  4. Todea barbara (½ nat. size).

Schizaeaceae. (Schizaea, Aneimia, Lygodium, Mohria.)

Sporangia borne singly and not in groups (sori), readily recognised by the complete transverse apical annulus usually one layer of cells deep, but occasionally two layers in depth on the side opposite the line of dehiscence[685] ([fig. 224], B). Schizaea ([fig. 222]) with the exception of one species in North America (S. pusilla) is characteristic of Northern India, the Malay region, Australia, New Caledonia, S. Africa, and elsewhere south of the Equator. Aneimia (figs. [223], [224], A, B), characterised by the fertile segments with reduced lamina, is chiefly American: the monotypic genus Mohria, resembling in habit the Polypodiaceous genus Cheilanthes, occurs in S. Africa and Madagascar, while species of Lygodium are widely spread tropical ferns, with one species in temperate North America. This family has disappeared from Europe.

Fig. 222. Schizaea elegans. (Slightly reduced.) A few of the segments terminate in narrow fertile lobes.

Fig. 223. Aneimia rotundifolia. (From the Royal Gardens, Kew. ⅓ nat. size.)