FILICES 8 1 



II. Sori dorsal. 



i. Involucre membranous, cup-shaped, at first enclosing the sorus, 

 afterwards splitting at the apex into several lobes. 



i S. A. species. Small, herbaceous. 11. W^oodsia 



i. Involucre resembling a scale, its wider end being under the 

 sorus and the other end turned over it like a hood. 



i species, C.fragi/is, cosmopolitan. 12. Cystopteris 



III. Sori linear, marginal, covered by a linear indusium, which 



opens outwards. 



1 tropical species in Natal. 13. Lindsaya 



b. Sori marginal. Indusium formed by the edge of the frond reflexed 



over the sorus and opening towards the midrib. 



I. Indusium terminal on the pinnule, reniform or elongated, bearing 



the sporangia on its under surface. "Maidenhair." 



1 1 species in S. A., of which A. thalictroides is frequent. 



14. Adiantum 



II. Sori in the sinuses between the lobes, reniform or oblong ; 



veins anastomosing. 



(1) 15. Lonchitis 



III. Veins free. Sori in the sinuses between the lobes or sometimes 



scattered. Indusia membranous, small, round, equal. 



3 species in S. A. 16. Hypolepis 



IV. Sori abundant, often confluent round the edge of the frond 



excepting the sinuses. Indusia roundish, not confluent, 

 formed of the edge of the frond, only partly inflexed. 



9 species in S. A. 17. Cheilanthes 



V. Sporangia arranged on the frond in a broad line, the indusium 



sub-continuous or sometimes interrupted and then consisting 

 of rounded portions. (Fig. 53.) 



7 species in S. A. 18. Pellaea 



VI. Sporangia in the axil of the indusium in a narrow line. 



Indusium quite continuous. 



8 species in S. A. (Incl. Pteridium.) 19. Pteris 



VII. Sori occupying the whole under side of the frond except the 



ribs. Indusium linear, continuous. Fertile pinnae narrower 

 than the barren. 



5 species in S. A. 20. Lomaria 



c. Sori not marginal, but covered by a linear or oblong indusium 



which opens towards the midrib. 



I. Sori linear, parallel with the midrib. 



2 species in S. A. 21. Blechnum 



M. II 



