FILICES 291 



3. POLYPODIUM. Polypody. 



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

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



P. vnlg^re, Linn. Common polypody or pohjpode. Figs. ,300, .307. 

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

 nearly or quite entire: fertile pinnse not contracted. 



4. ADIANTUM. Maidenhair Fern. Fig. 309. 



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

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

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



A. pedd.tum, Linn. Common maideyihair. Plant 2 ft. or less high, 

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

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



5. PT£:RIS. Brake. 



Coarse ferns of mostly dryish places, with long pinnae: sporangia borne 

 beneath the reflexed margin of the pinnules, on small, transverse veins. 



P. aquillna, Linn. Common brake. Figs. 125, 308. Fronds broadly 

 triangular, twice- or thrice-pinnate, the pinnules long-lanceolate, acuminate, 

 and lobed. Common in sunny places: perhaps our commonest fern. Two 

 to 3 ft. high, growing in patches, particularly in burned areas. 



6. ASPLfiNIUM. Spleen WORT. 



Middle-sized ferns, mostly with pinnate leaves: sori oblong or linear, 

 borne on the upper side of a veinlet, or back to back on opposite sides of 

 the veinlet, these veinlets not interwoven. 



A. Filiz-foeiuiiia, Linn. Lady-fern. Large, the fronds 2-3 ft. tall, 

 growing many together, twice-pinnate, the pinnules oblong-pointed and 

 sharp-toothed: sori short and close together, at matiirity becoming more 

 or less continuous. A very common fern in moist woods and copses. 



7. DRYOPTERIS. Shield-fekn. 



Much like the last in general appearance, but the sori circular and 

 covered with peltate or reniform indusia. 



D. acrostichoides, Kuntze. (Aspidinm acrostichoides, Swartz). 

 Christmas fern. Figs. 304, 305. Fronds 2 ft. or less tall, narrow, once- 

 pinnate, the pinnae serrate and bearing a larger tooth on the upper side 

 near the base, the terminal part of the frond 

 somewhat contracted in fruit. [Common la 

 woods. Nearly or quite evergreen. 



D. Thelypteris, Gray. (Aspidium The- 

 lypteris, Sv^&rtz). Marsh shield-fern. Fronds 

 standing 2 ft. high, long-pointed, once-pin- 

 nate, the pinnae many-lobed, the margins of 

 the fertile fronds revolute. 



420. Dryopteris^mTrginalis. , ^- ^^^^i^^^^^, Gray. Fig. 420. Large, 

 handsome fern growing in woods and ravines, 

 2 ft. high: fronds once-pin-nate, the pinnte pinna*itied and lance-acuminate: 

 sori large and close to the margin of the frond: petiole chaflfy. 



