290 



THE KINDS OF PLANTS 



BB. Sporangia with a ring of prominent elastic cells run- 

 ning around the margin, and which are concerned 



in the dehiscence (as in Fig. 307) 2. Onoclea 



AA. Fruit borne on the back of green fronds (the fruiting 

 pinnae sometimes narrowed but still leaf-like, as in 

 Fig. 305): sporangia with a ring of elastic cells. 



B. Sori naked (no indusium) 3. Pohjijodium 



BB. Sori borne under the reflexed margins of the frond, 

 c. FinnfB entire on the lower edge, somewhat trian- 

 gular in outline 4. Adiantum 



cc. Pinnae toothed on both margins, oblong in outline. ..5. Pteris 

 BBB. Sori covered with a distinct scale-like indusium. 



c. Shape of sori oblong C. Asplenium 



CO. Shape circular, indusium peltate or nearly so 7. Dryopteris 



1. 0SMl3'NDA. Flowering Fern. 



Strong ferns from stout creeping rootstocks, with large pinnate fronds: 

 sporangia covered with interwoven ridges, but wanting the elastic ring of 

 most ferns. Inhabitants of bogs and wet woods. 



0. regMis, Linn. Eoyal fern. Top of the frond contracted into a 



fruiting panicle: frond 2-piunate, the pinnaa oblong, olituse, and nearly entire. 



0. Claytoniana, Linn. 



Fig. 418. Two to four pairs 



of pinnae near the middle of 



the frond contracted into 



^' Awijy ^,;^-, fruit-bearing parts : pinnae '^^f^W( -^ ,p-^^!^^^*^ 



'^^^^^ J^S\'J^T^ linear-lanceolote and acute, '^i#4,^^llllC!?\ £i/-?'6't*ak. 



<»^.*^^M|^ deeply lobed. W^JFIlvC.^'^"^^^ 



^^'" 0. cinnamdmea, Linn. '^'^^?^^^^^},'^^'^ 



Cinnamon fern. Fig. 419. 



,, , ^ , ^, Some fronds entirely con- 



418. Osmiinda Clay- . a ■ ^ t •4.- 



..■„„„ tracted into fruiting parts, , „ ^ , . 



and these cinnamon color 



(whence the \ernacular name): sterile form with the fronds much like 



those of O. Calytoniana in shape except more acute at top. 



2. ONOCLfiA. Sensitive Fern. 



Mostly rather strong ferns, with broad sterile fronds and with the fer- 

 tile fronds rolled into hard contracted fruiting bodies, which remain after 

 the steril3 leafy fronds have perished: sporangia with an elastic marginal 

 ring of cells. Bogs and old springy fields. 



0. sensibilis, Linn. Sensitive fern. Brake. Fig. 310. Sterile frond 

 triangular-ovate, the pinnae not extending quite to the midrib and toothed: 

 fertile frond usually lower than th3 other (1-2 ft. high), with a few pinnae. 

 Common in old pastures. 



0. 8trutlii6pteris, Hofifm. Ostrich fern. Very tall (2-5 ft.), the sterile 

 fronds narrow, once-pinnate, with long-lanceoUite acute lobed pinnaj: fer- 

 tile fronds much shorter, blackish, with many pinnae. 



