99. FILICES. 41 



Order XCIX. FILICES. 



Leafy plants with a rhizome or trunk. L. or fronds with a 

 circinate vernation (Tribe VII. excepted), simple or divided. 

 Fructification springing from the veins on the under side or at 

 the edge of the L, of 1 -celled capsules (thecse) which are stalked 

 and have an elastic ring or sessile and without a ring. 



* Capsules with an elastic marginal ring. 

 Suborder I. POLYPODIACE^. 



Capsules in clusters xm the back of the frond, opening trans- 

 versely ; ring vertical, usually incomplete. 



Tribe I. POLYPODIES. Clusters nearly circular, without 

 an indusium, seated upon the back of the lateral veins. 



1. ALLOSORUS. Clusters circular, at length confluent, con- 

 cealed by the reflexed margin of the frond. 



2. POLYPODIUM. Clusters circular, naked; edge of the 

 frond flat, not reflexed. 



3. WOODSIA. Clusters circular, with an inferior involucre 

 divided at the edges into many capillary segments. 



Tr. II. ASPIDIE^E. Clusters nearly circular, covered by an 

 indusium, seated upon the back of the lateral veins. 



4. LASTREA. Indusium reniform, attached by the sinus. 

 Veins distinct after leaving the midrib, not uniting with 

 those of the adjoining lobe. 



5. POLYSTICHUM. Indusium circular, attached by the centre. 

 Veins distinct after leaving the midrib. 



6. CYSTOPTERIS. Indusium attached by its broad hooded 

 base under the clusters, with a long fringed free extremity 

 at first covering the capsules. 



7. PSEUD ATHYRIUM. " Indusium crescentic, oblique, at- 

 tached across the vein by its inner edge." (Newm.) 



Tr. III. ASPLENIEsE. Clusters oblong or linear, usually 

 covered by an indusium opening longitudinally on one side, 

 placed on the side of the lateral veins. 



8. ATHYRIUM. Clusters oblong-reniform. Indusium open- 

 ing towards the central vein or midrib, margin fringed. 



9. ASPLENIUM. Clusters long, straight. Indusium opening 

 towards the central vein or midrib, nearly flat. % 



T5 



