488 



FILICES. 



Pteris. 



5. PTERIS. Linn. ; Agardh, sp. gen. Pterid. ; J. Smith, I. c. no. 60. BRAKE. 



[From the Greek, ptcryx or pteron, a wing or feather ; in allusion to the form of tho frond.] 



Sori marginal, linear, continuous or interrupted, formed of a transverse receptacle which 

 connects the apices of the veinlets. Involucre linear, narrow, occupying the margin of the 

 frond ; the inner side free. — Fronds varying from pinnate to decompound ; the segments 

 usually lobed or pinnatifid. Veins mostly forked ; the branches direct, their apices united 

 in the receptacle of the capsules. 



1 . Pteris Aquilina, Linn. Common Brake, or Bracken. 



Frond 3-parted, the branches bipinnate ; pinnulos oblong-lanceolate, the lower ones pinnatifid, 

 upper ones entire ; segments oblong, obtuse. — Linn. sp. 2. p. 1075 ; Michx. fl. 2. p. 262 ; 

 Pursh, fl. 2. p. 688 ; Bigel. fl. Bost. p. 391 ; Torr. compend. p. 384 ; Beck, hot. p. 445; 

 Darlingt. fl. Cest. p. 583 ; Agardh, I. c. p. 49 ; Hook. fl. Bor.-Am. 2. p. 263. P. caudata, 

 Pursh, I. c. excl. syn. 



Stipe 1-2 feet long, smooth, angular, light brown. Frond 1 — 24 feet in diameter, 

 bi-triternately divided, somewhat coriaceous, dull green ; the pinnules 1-2 inches long : 

 lower ones of each division more or less pinnatifid ; some of them with only a few lobes, or 

 a single lobe on the lower side of the base, giving them an auricled appearance. Sori un- 

 interrupted ; the receptacle thickened. Involucre narrow. 



Woods and thickets : very common. Fr. July - August. Our plant agrees in every 

 respect with my European specimens. 



6. PLATYLOMA. J. Smith, I. c. no. 53. platyloma. 



[From the Greek, plalys, broad, and loma, a fringe; in allusion to the broad marginal sori.] 

 Species of Pteris, Linn. <f- others. 

 Sori oblong, laterally confluent, constituting a broad continuous compound marginal sorus. 

 Involucre marginal and continuous ; the inner margin free. — Fronds pinnate or bipinnate : 

 pinnae stalked. Veins forked ; the veinlets direct, free at their apices, bearing capsules 

 along a portion of the upper part, and, being closely approximated, form a broad compound 

 sorus. 



Differs from Pteris, in the apices of the veinlets being free, not combined by a transverse receptacle. 



I. Platyloma atropurpurea, J. Sm. Purple-stalked Rock-brake. 



Frond pinnate or somewhat bipinnate, the lower divisions ternate or pinnate ; segments 

 oblong, obtuse, entire, obliquely truncate or cordate at the base ; stipe a little hairy. — /. 

 Sm. I. c. ; Linn. sp. 2. p. 1076 ; Michx. fl. 2. p. 261 ; Pursh, fl. 2. p. 668 ; Torr. compend. 

 p. 384 ; Beck, hot. p. 454 ; Agardh, I. c. ; Darlingt. fl. Cest. p. 583. 



