14 FLORA. 



and shorter ; son' large, at length contiguous, l>orne nearer the margin than the 

 midrib. On rocks. Lab. to Alaska, south to Ont. and Br. Col., and in the 

 Rocky Mts. to Utah. Also in X. Europe and Asia. 



2. Polystichum acrostichoides (Michx.) Schott. Christmas Fern. (I. F. 

 f. 2j.) Rootstock stout, creeping. Stip.s 12-16 cm. long, densely chaffy ; leaves 

 lanceolate, I.5-6 dm. long, 7-12 cm. wide, rigid, evergreen, subcoriaceous, once 

 pinnate ; pinnae linear-lanceolate, somewhat falcate, 2.5-7 cm. long, acutish at the 

 apex, half halberd-shaped at the base, bristly with appressed teeth, the lower 



scarcely smaller ; fertile fronds contracted at the summit, bearing ihe large con- 

 tigUOUS sori near the middle, which soon cover the whole lower surface. In woods 

 and rocky places. \\ B. and N. S. to Fla., west to Ont., Wis., and Miss. July- 

 Aug. Forms with CUt-lobed or incised pinnx are known as var. Schweinitzii ; 

 Occasional forms are 2-pinnatifid. 



3. Polystichum Braunii (Spenner) Fee. (I. F. f. 28.) Rootstock stout. 

 Stipes 10-12 cm. long, chaffy with both broad and narrow brown scales ; leaves 

 oblong-lanceolate, not coriaceous, 2-pinnate, tin- rachis chaffy, at least below ; 

 pinnae numerous, close together, lanceolate or linear-lanceolate, broadest at the 

 base, cut to the midvein into ovate or oblong pinnules ; middle pinnee 6-10 cm. 

 long, the lower gradually shorter ; pinnules truncate and nearly rectangular at the 

 base, acute or obtuse, sharply toothed and beset with long soft hairs and scales ; 

 sori small, mostly nearer the midvein than the margin. In rocky woods, Quebec 

 to Alaska, south to Me., the mountains of Penn., Mich, and Br. Col. Aug. 



13. DRYOPTERIS Adans. [ASPIDIUM Sw.] Shikld-fkrn. 



Ferns with 2-3 -pinnate or pinnatifid leaves and round sori usually borne on the 

 backs of the veins, the fertile and sterile leaves similar in outline. Indusium 

 flattish, cordate reniform, superior, fixed by its sinus. Stipe continuous, not 

 jointed with the rootstock. Veins free. [Greek, signifying oak-fern, in allusion 

 to the forest habitat of most species.] About 150 species, of wide distribution. 



Texture thin-membranous ; veins simple or once forked ; leaves pinnatifid. 

 Lower pinnae very much reduced. 

 Lower pinnae little smaller than the middle ones. 



Veins 1-2-forked ; sori crowded, 10-12 to a segment. 

 Veins simple ; sori larger, distant, 4-10 to a segment. 

 Texture firmer, sometimes subcoriaceous; veins forking freely. 

 Leaves 2-pinnatifid or 2-pinnate ; segments not spinulose. 

 Leaves small, narrowly lanceolate. 

 Leaves larger, mostly 0.4-1.6 m. high. 

 Indusia lar<;e, thinnish and flat. 

 Pi 111132 widest at the base. 

 Pinnae widest at the middle. 

 Indusia convex, without marginal glands. 

 Sori near the margin. 

 Sori near the midvein. 

 Leaves 2-pinnate or 3-pinnatifid ; segments spinulose-toothed. 



Leaves ovate-lanceolate, usually not narrowed below ; scales of stipes usually 



with a dark centre. 9. D. spinulosa. 



Leaves elongated-lanceolate, usually narrowed at the base ; scales of the stipes 

 pale brown. 10. D. Boottii. 



1. Dryopteris Noveboracensis (L.) A. Gray. (I. F. f. 29.) Rootstock 

 slender, creeping. Leaves lanceolate, tapering Kith ways from the middle, 3-6 dm. 

 long, 10 15 cm. wide, membranous, long-acuminate at the apex, once pinnate; pinnae 

 lanceolate, senile, long acuminate, deeply pinnatifid, filiate and finely pubescent 

 beneath. 37 cm. loin:, the two ,,r more lower pairs gradually shorter and dehVxed. 

 commonly distant ; segments flat, oblong, obtuse, the basal ones often enlarged; 

 veins simple or those of the basal lobes forked; sori not confluent, borne near the 

 margin; indusium minute, reniform, delicate, glandular. In moist woods. Newt. 

 to I >nt. and Minn.. BOUth to C.a., Ala. and Ark. 



2. Dryopteris Thelypteris (I ..) L Gray. (I. 1. f. 30.) Rootstock slender, 

 creeping. Leaves lanceolate or oblong lane arcely narrower at the base 

 than at the middle, 3 8 dm. long, 10-15 cm. wide, short-acuminate, membranous, once 



I. 



D. Noveboracensis. 



2. 

 3- 



D. Thelypteris. 

 D. sijnulata. 



4- 



D.fragrans. 



5- 



6. 



D. cristata. 

 D. Goldieana. 



7- 

 S. 



D. margin a lis. 

 D. Filix-mas. 



