FiLiCES. (ferns.) 68'J 



§ 2. POLYSTICnUM. Tiidusiitm orbicular and entire, peltate, fixed by the 

 depressed centre ; fronds rigid and coriaceous, evergreen, very chaffy on the 

 rhachis,etc.; pinnce or pinnules auricled at base on the upper side, crowded, 

 the teeth or lobes bristle-tipped. 



* Fronds simjily pinnate. 



10. A. acrostichoides, Swartz. (Chuistmas Fern.) (Tl. 19, fig. 3, 4.) 

 Frond lanccolati! (l-:ijj'' I'ii^lO) stalked; pinnce, linear-iauceolate, somewhat 

 scythe-shai)cd, lialf-lialbord-sliaped at the sliglitly stalked hase, serrulate with 

 appressed bristly tectli ; the fertile (upper) contracted and smaller, beariug con- 

 tiguous fruit-dots near the midrib, which are confluent with age, covering the 

 surface. — Var. iNcisuM is a state with cut-lobed pinnai, a not unfrequent case 

 in the sterile fronds ; sometimes with all the tips fertile. — Common in rocky 

 woods, especially northward. July, 



11. A.Lonchitis, Swartz. Frond linear-lanceolate (9-20' high), scarce/^ 

 stalked, very rigid ; pinnce broadly lanceolate-scythe-shaped , or the lowest trian- 

 gular, strongly auricled on the upper side, and wedge-truncate on the lower, 

 densely spinulose-toothed (!' or less in length), copiously fruit-bearing; fruit- 

 dots contiguous and near the margins. — Woods, southern shore of Lake Su- 

 perior, and northward. (Eu.) 



* * Fronds bipinnnte. 



12. A. aculeatum, Swartz, var. Braiinii, Koch. Fronds spreading 

 (1^-2^ l<^"i?)> oblong-lanceolate in outline, with a tapering base, the lower of 

 the many pairs of oblong-lanceolate pinna gradually reduced in size and ob- 

 tuse ; pinnules ovate or oblong, obtuse, truncate and almost rectangular at 

 base, short-stalked, or the upper confluent, sharply toothed, beset with long 

 and soft as well as chaffy hairs. — Deep woods, mountains of New Eng., N. Y., 

 and Penn., and northward. (Eu.) 



14. CYSTdPTERIS, Bernhardi. Bladder Fern. (PI. 19.) 



Fruit-dots roundish, borne on the back of a straight fork of the free veins; 

 the delicate indusium hood-like or arched, attached by a broad base on the in- 

 ner side (toward the midrib) partly under the fruit-dot, early opening free at 

 the other side, which looks toward the apex of the lobe, and is somewhat 

 jagged, soon thrown back or withering away. — Tufted ferns witli slender 

 and delicate 2-3-pinnate fronds; the lobes cut-toothed. (Name composed of 

 Kvaris, a bladder, and irTepisyfern, from tlie inflated indusium.) 



1. C. bulbifera, Bcrnh. (PI. 19, fig. l -3.) Frond lanceolate, elongated 

 (1 -2° long), 2-])innate; the pinnse lanceolate-ol)long, pointed, horizontal (1 - 

 2' long); the rhachis and pinnoi often bearing bulblds underneath, tringless ; 

 pinnules crowded, oblong, obtuse, toothed or pinnatifid ; indusium short, trun- 

 cate on the free side. — Shaded ravines, not rare from N. Eng. to Ark., com- 

 moner on calcareous rocks. July. — Specimens from Tenn. and Ark. have 

 sometimes shorter fronds and few or no bulblets, indicating an approach to the 

 next species. 



2. C. fr^gilis, Bernh. Frond oblong-lanceolate (4-8' long, besides the 

 brittle stalk which is fully as long), 2 -3-pinuate ; the pinnaj and pitinules ovata 

 or lanceolate iu outline, irregularly pinnatifid or cut-toothed, mostly acute, 



