462 THE FAMILIES, GENERA AND SPECIES OF PTERIDOI'H VTA. 



('.roup 1. — Sori distant from the mar.iiin or covering" the 



whole undersurface. 

 Sori orbicular or reniform. 

 Sori orbictilar. 



Indiisiuni present (deciduous in some species of 

 Aspidiimi). 



Indusium underneath the sorus i. Woodsia. 



Tndusium covering the sorus 2. Aspidium. 



Indusium absent 18. Polypodium. 



Sori reniform. 



Leaves 2-pinnatitid 3. Nephrodium. 



Leaves simple 4. Oleandra. 



Sori elongated, linear or rarely oblong" or in patches. 

 Sori forming" patches, covering" the whole (or a part) 



of the under-surface of the leaf ... 19. Acrostichum. 

 Sori not in patches. 



.Sterile and fertile leaves dissimilar 6. Lomaria. 



vSterile and fertile leaves similar. 



Sori not on the vein, but in a continuous line on 



each side of the vein 7. Blechnum. 



Sori arising from the veins. 



Indusium distinct, attached along one side of 

 the vein and opening along the other 



side 8. AsPLENiUM. 



Indusium al)sent 9. Gvmxogramme. 



Croup 2. — Sori marginal. 



Indusium absent 11. Nothochl.ex.\. 



Indusium present. 



Indusium opening" outward (toward the margin). 



5. Davallia. 

 Indtisium opening inward (toward the rachis). 

 .Sori and indusia linear (see also 12, Ciikilaxthes). 



Veining fan-like 14. Adiantum. 



Alining not fan-like. 



Sori and indusia not absolutely contii"iuous. 



10. Pele.^:a. 

 Sori and indusia quite continuous. 



Sori occupying the edge of the segments. 

 Leaves small and rigid, and like a Fan- 

 palm in miniature 15. Actixiopteris. 



Leaves large and herbaceous: Ijarren and 



fertile nearly alike 16. Pteris. 



Sori confii"ied to the sinuses of the leaf. 



17. LOXCHITIS. 



.Sori globose or reniform. 



N'eining fan-like 14. Adiaxtum. 



\'eining not fan-like. 



Sori confined to the sinuses of the leaf. 



13. Hypolepis. 

 Sori crowded round the edge of the leaf, ex- 

 cept at sinus 12. Cheilaxthes. 



