464 FILICES. 



A. pf datum Linn. : frond pedate ; divisions pinnate ; segments dimidiate, 

 triangular-oblong, or somewhat rhomboid ; the upper margin incisely lobed 

 and serrate ; sori somewhat lunate. 



Shady woods. Can. to Virg. W. to Miss, and Louis. July. 9.J.. A delicate 

 and graceful fern 1 2 feet high, easily known by its long slender black highly 

 polished stipe, and its pedate nearly horizontal frond. Maiden-hair. 



12. CHEILANTHES. Swartz. Cheilanthes. 



(From the Greek %<Aoj, a lip, and avOo$, a, flower; in allusion to the labiate 

 form of the indusium.) 



Sori roundish, distinct, situated at the margin of the frond. 

 Indusium of distinct membranaceous inflexed scales, opening 

 inwards. 



C. vestita Willd. : frond bipinnate, hairy on both sides ; pinnules pinna- 

 tifid ; segments rounded, oblong, very entire ; stipe and rachis hairy. 



Rocky banks. Penn. to Car. W. to the Rocky Mountains. July. 1. Fern 

 6 8 inches high, covered with long brownish hair. Stipe somewhat rigid. 

 Frond lance-oblong in its outline. Sori at length contiguous or crowded. 



Hairy Cheilantkes. 



13. HYMENOPHYLLUM. Smith. Filmy Fern. 



(Prom the Greek v^v, a membrane, and <t>XAoi/, a leaf; in allusion to the tex- 

 ture of the frond.) 



Sori in separate spots on the the margin of the frond. Spore- 

 cases inserted upon a narrow receptacle, within a 2-valved indu- 

 sium which is of the same texture as the frond, opening above. 



H. ciliatum Smith : frond pinnate ; lower divisions larger ; upper ones 

 gradually smaller, pinnatifid ; segments linear-obtuse, bifid, ciliate, hairy 

 on the veins ; stipe and rachis winged and ciliate. Tiichomants ciliatum 

 Swartz. 



Trunks of trees in shady places. Penn. and Virg. 1\.. Pursh. 



Ciliate Filmy-fern. 



14. STRUTHIOPTERIS. Willd. Ostrich Fern. 



(From the Greek orpou0dj, an ostrich, and irrefus, a fern ; on account of the 

 fancied resemblance to the plumes of that bird.) 



Fertile frond contracted ; the margins revolute, forming a 

 general involucre. Sori round, confluent, naked ; the pedicels 

 of the spore-cases cohering at the base, forming an elevated 

 thickened receptacle. 



<S. Germanica Willd. : sterile frond pinnate ; pinnse pinnatifid, sessile ; 

 segments entire, rather acute, lower ones elongated. S Pennsylvanica 

 Willd. Onocka Struthiopteris and nodulosa Schk. 



Low grounds. Can. N. Eng. and N. Y. ; lather rare. July. TJ.. Sterile 

 fronds 23 feet high, forming circular tufts. Fertile fronds central, much 



