FILICES 285 



1. OSMtfNDA. 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. regalis, Linn. Royal fern. Top of the frond contracted into a 

 fruiting panicle : frond 2-pinnate, the pinnae oblong, obtuse, and nearly entire. 



0. Claytoniana, Linn. 

 Fig. 418. Two to four pairs 

 of pinnae near the middle of 

 the frond contracted into 

 fruit-bearing parts : pinnae 

 linear-lanceolote and acute, 

 deeply lobed. 



0. cinnamdmea, Linn. 

 Cinnamon fern. Fig. 419. 



Some fronds entirely con- 

 418. Osnmnda Clay- J 



tracted into fruiting parts, 



toniana. > 419. Osmunda cinnamomea. 



and these cinnamon color 



(whence the vernacular 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 sterile leafy fronds have perished : sporangia with an elastic marginal 

 ring of cells. Bogs and old springy fields. 



0. sensfbilis, 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 the other (1-2 ft. high), with a few pinnae. 

 Common in old pastures. 



0. Struthidpteris, Hoffm. Ostrich fern. Very tall (2-5 ft.), the sterile 

 fronds narrow, once-pinnate, with long-lanceolate acute lobed pinnae: fer- 

 tile fronds much shorter, blackish, with many pinnae. 



3. POLYPODIUM. POLYPODY. 



Small ferns, with simple or once-pinnate fronds from slender creeping 

 rootstocks: sori round, borne at the ends of little veins. On dry cliffs. 



P. vulgare, Linn. Common polypody or polypode. Figs. 306, 307. 

 Fronds a foot or less tall, narrow-oblong in outline, pinnatifid, the lobes 

 nearly or quite entire: fertile pinnae not contracted. 



4. ADlANTUM. MAIDENHAIR FERN. Fig. 309. 



Small ferns with compound forking fronds and wedge-shaped or some- 

 what triangular pinnae, shining stipes or petioles, and sori borne at the 

 ends of the veins under the reflexed margins of the pinnae. 



A. pedatum, Linn. Common maidenhair. Plant 2 ft. or less high, 

 the leaves forking into several or many long pinnae which bear broad pin- 

 nules notched on the upper margin. Cool, shady woods. Very graceful. 



