392 ACROGENOUS PLANTS 



g 2. PTERIDEAE : Sori covered by a special indusium, which is marginal, and laterally 

 continuous, or sometimes interrupted. 



512. PTE^RIS, L. 



[Gr. Pteron, a wing; a name given to Ferns, on account of their -winged fronds.] 

 Sori linear, continuous laterally in a line which borders the divisions 

 of the frond, the indusium fixed at the very margin, with the inner 

 edge free ; veins forked and free, bearing the sporanges at their apex. 

 Fronds subcoriaceous, pinnately dissected. 



! I", aquilina, L. Frond 3-parted, on a tall erect stout stipe; 

 branches bipinnate; pinnules lance-oblong; indusmm narrow. 

 AQUILINE PTERIS. Brake, or Bracken. 



Fronds 1 to 3 feet long, decompound, spreading; pinnae oblong-lanceolate; 

 Stipe, 1 to 2 feet high, angular, smooth, tawny. Sori resembling a narrow russet 

 border, or hem, along the edge of the pinnules, on the under side. 

 Hob. Moist woodlands, and thickets : frequent. Fr. July, Aug. 

 2. I". at ropurpikrca, L. Frond simply pinnate, or sub- 

 bipinnate, on a short dark purple stipe ; pinnae obliquely truncate, 

 or subcordate, at base. 

 DARK-PURPLE PTERIS. 



Fronds 3 to 6 or 8 inches long, and 1 to 3 or 4 inches wide across the lower divi- 

 sions, which are often ternate, or odd-pinnate in fives or sevens; pinnae and pin- 

 nules subsessile, varying from oval to linear-oblong; stipes 2 to 4 inches long, 

 terete, often numerous, with a dense tuft of tawny-ferruginous chaffy hairs at 

 base. 

 Hob. Limestone rocks; Great Valley: rare. Fr. July. 



513. AIMTAIVT'IJM, L. 



[Gr. a, not, and diaino, to moisten ; its surface repelling rain-drops.] 

 Sori oblong, of somewhat lunate, interrupted, occupying the edge 

 of the pinnae, or lobes of the frond, 4he indusium appearing as a 

 reflexed portion of its margin, bearing the sporanges on its under 

 side, on the free ends of the simply forking veins. Stipe and rachis 

 black and polished. 



1. A. pedatum, L. Frond forked, the forks pedately branch- 

 ing ; divisions pinnate ; pinnae semi-rhomboid, stipitate, the upper 

 margin incisely lobed. 

 PEDATE ADIANTUM. Maiden's Hair. 



Fronds 6 to 9 inches long, and 9 to 12 inches wide, glabrous, pale bluish-glaucous 

 green ; pinnae % of an inch to an inch long, entire on the lower margin, as if 

 halved ; stipes 6 to 12 or 15 inches high, slender, compressed, chaffy at and near 

 the base. 

 Hob. Rich, rocky woodlands: frequent. Fr. July. 



514. CHEttAtfTIIES, Swartz. 



[Gr. Cheitos, a lip, and anthos, a flower; from the shape of the indusium.] 

 Sori roundish, solitary, or contiguous, on the margins of the pinnule- 

 lobes; indusium usually reniform, fixed to the margin at the point 

 where the sporanges arise, free along the inner edge. Frond bi- tri- 

 pinnatifid; stipe roughish-hairy. 



1. C. vestita, Willcf. Fronds bipinnate, hairy on both sides ; 



