586 FILICES. (ferns.) 



celled, borne on the under side of the fronds or along their margins, often 

 covered by a membrane of various shape (indusium or involucre), contain- 

 ing numerous exceedingly minute spores. 



Synopsis. 



Suborder I. POLYPODINEJE. Sporangia collected in dots, lines, 

 or variously shaped clusters (sori or fruit-dots), or in indefinite masses, 

 ct'lliilar-reticulated, mostly pedicelled ; the stalk running into a vertical 

 Incomplete elastic ring, the straightening of which ruptures the ripe 

 sporangium on the inner side, discharging the spores. — Fronds simple 

 or variously divided. 



Tribe I. ACROSTICHEiE. — Sporangia collected in large or indefinite masses on the 

 back of the frond : indusium none. 



1. ACR0STICI1UM. Sporangia covering the lower surface of the upper pinnae. Veins retic- 



ulated. 



Tribe II. POLYPODIE^E. — Fruit-dots roundish, distinct, destitute of indusium, 

 borne on the back of the frond. 



2. POLYPODIUM. Fruit-dots scattered variously on the back of the frond, borne at or near 



the ends of the veins. 



Tribe III. — VITTARIE^E. — Sporangia borne in a continuous elongated marginal or 

 sub-marginal furrow. 



3. V1TTARIA. Fronds simple, narrowly linear. 



Tribe IV. PTERIDE^I. — Fruit-dots marginal, separate or continuous. Indusium 



formed by the reflexed margin of the frond or its lobes, opening toward the midrib. 

 * Indusium thin and membranaceous, continuous around the margin of the fertile pinnae. 



4. PTERIS. Sporangia borne on a transverse intramarginal veinlet. 



5. PELLJEA. Sporangia borne on the ends of the veins, at length confluent. 



* * Indusium rarely continuous, mostly formed of the reflexed ends of the lobes or divisions 

 of the pinn* or pinnules. 



6. CIIETLANTIIES. Sporangia borne on the veins beneath the reflexed margin of the 



frond. Pinnules with a midrib. 



7. ADIAN'JTM. Sporangia borne on the under side of the indusium. Midrib none or 



eccentric. 



Tribe V. BLECHNE^B. — Fruit-dots dorsal, linear or oblong, borne on transverse 

 veins parallel to the midrib. Indusium fixed by its outer margin, and opening at the 

 inner one. 



8. BLECHNUM. Fruit-dots linear, elongated, covered by a continuous indusium. 



9. WOODWARDIA Fruit-dots linear-oblong, in a series near the midrib, covered by sep- 



arate indusia. 



Thibe VI. ASPLENIEJE. — Fruit-dots dorsal, linear or oblong, oblique or at right 

 angles to the midrib. InduMiun fixed by one margin to the veinlet, opening at the 

 other. 



10. CAMPTOSORU8. Fruit-dots straight or curved, nattered irregularly oa the more or less 



reticulated veins, ox facing each other in pairs. Frond simple. 



11. ASM. KM I'M. Kruit-dots oblique, on the upper side of the veins, rarely on both sides of 



them. Veins free. 



