12 



POLYPODIACEAE. 



3. DICKSONIA L'Her. Sertum Angl. 30. 1788. 



Large ferns with 2-3-pinnatifid leaves, and creeping or erect rootstocks, many tropical 

 species arborescent. Son small, globular, marginal or submarginal. Sporanges borne in 

 an elevated globular receptacle, enclosed in the membranous cup-shaped inferior indusium 

 which is open at the top and on the outer side adherent to a reflexed toothlet of the leaf. 

 Sporanges pedicelled, provided with a vertical ring which bursts transversely. Veins always 

 free. [Name in honor of James Dickson, English nurseryman and botanist, 1738-1822.] 



About 50 species, of wide distribution, the greater number in tropical America and Polynesia. 



i. Dicksonia punctilobula ( Michx. ) A. Gray. Hay-scented Fern. (Fig. 22.) 



.\ff>linniiuni pHuclilobitlnm Michx. Fl. Bor. Am. 2 : 



Ditkwuia />iJi>siHSCnIa Willd. Knum. 1076. 1809. 

 nifksonia pnnctilobnla A. Gray, Man. 628. 1848. 



Rootstock slender, extensively creeping, not 

 chaffy. Stipes stout, chaffless, pale green and 

 sweet-scented ; leaves i-3 long, 5 '-9' wide, ovate- 

 lanceolate, acute or acuminate, frequently long- 

 attenuate, usually 3-pinnatifid, thin and delicate ; 

 rachis and under surface minutely glandular and 

 pubescent ; son minute, each on a recurved tooth- 

 let, usually one at the upper margin of each lobe ; 

 sporangcs few; indusium cup-shaped with a delicate 

 membranous irregular margin. 



In various situations, most abundant on open hill- 

 sides. New Brunswick and Ontario to Indiana and Min- 

 i (according to Upham), south to Alabama and 

 Tennessee. Ascends to 5600 ft. in Virginia. Aug. 



1806. 



4. CYSTOPTERIS Bernh. Schrad. Neues Journ. Bot. i: Part 2, 26. 



Delicate rock ferns with slender stipes, 2-4-pinnate leaves, and roundish son borne on 

 the backs of the veins. Indusium membranous, hood -like, attached by a broad base on 

 its inner side and partly under the sorus, early opening and somewhat evanescent. Veins 

 free. Sporanges pedicelled, provided with a transversely bursting vertical ring. [Greek, 

 signifying Bladder-fern, in allusion to the inflated indusium.] 



Five species, natives of the north temperate zone. Only the following known in North America, 



leaves ovate-lanceolate or lanceolate, 2-3-pinnate. 



Leaves broadest at base, long-tapering, bearing bulblets beneath. 



cely broader at base, short-pointed; no bulblets. 

 Leaves deltoid-ovate, 3-4-pinnate. 



1. C. bulbifera. 



2. C. f raff His. 



3. C. montana. 



i. Cystopteris bulbifera (L. ) Bernh. 

 Bulblet Cystopteris. (Fig. 23.) 



Poly podium bulbifcrum L,. Sp. PI. 1091. 1753. 



Cystopteris bnlbifera Bernh. Schrad. Neues Journ. 

 "Bot. i: Part 2, 26. 1806. 



Rootstock short, copiously rooting. Stipes 4 / -6 / 

 long, light colored; leaves elongated, lanceolate 

 from a broad base, i-2% long, 2-3-pinnatifid or 

 pinnate ; pinnules crowded, toothed or pinnatifid ^ 

 rachis wingless, commonly bearing underneath in 

 the axils of the pinnae and segments, large fleshy 

 bulblets which fall away and propagate the plant ; 

 indusia short, truncate on the free side, early 

 thrown back and withering so that the sori appear 

 naked at maturity. 



On wet rocks and in ravines, especially on limestone, 

 Quebec to Wisconsin, south to Tennessee and Arkansas. 

 Ascends to 3500 ft. in Virginia. July-Aug. 



