14 FLORA. 



and shorter"; sori large, at length contiguous, borne 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 N. Europe and Asia. 



2. Polystichum acrostichoides (Michx.) Schott. CHRISTMAS FERN. (I. F. 

 f. 27.) Rootstock stout, creeping. Stipes 12-16 cm. long, densely chaffy ; leaves 

 lanceolate, 1.5-6 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 the large con- 

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

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

 Aug. Forms with cut-lobed or incised pinnae are known as var. Sckweinitzii ; 

 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, the 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 pinnae 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. SHIELD-FERN. 



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. i. D. Noveboracensis. 

 Lower pinnae little smaller than the middle ones. 



Veins i-2-forked ; sori crowded, 10-12 to a segment. 2. D. Thelypteris. 



Veins simple ; sori larger, distant, 4-10 to a segment. 3. D, simulata. 

 Texture firmer, sometimes subcoriaceous ; veins forking freely. 

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



Leaves small, narrowly lanceolate. 4. D.fragrans. 

 Leaves larger, mostly 0.4-1.6 m. high. 

 Indusia large, thinnish and flat. 



Pinnae widest at the base. 5. D. cristata. 



Pinnae widest at the middle. 6. D. Goldieana. 

 Indusia convex, without marginal glands. 



Sori near the margin. 7. D. marginalis. 



Sori near the midvein. 8. D. Filix-mas. 

 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 both ways from the middle, 3-6 dm. 

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

 lanceolate, sessile, long-acuminate, deeply pinnatifid, ciliate and finely pubescent 

 beneath, 3-7 cm. long, the two or more lower pairs gradually shorter and deflexed, 

 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, Newf. 

 to Ont. and Minn., south to Ga., Ala. and Ark. 



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

 creeping. Leaves lanceolate or oblong-lanceolate, scarcely narrower at the base 

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



