18 PERNS OF GREAT BRITAIN. 



16. Htmenophyllum (Pilmy Fern). — Fructification 

 on the margin of tlie fern; the clusters seated within 

 a 2-valved involucre, which is an expansion of the frond. 

 Name from the Greek, hymen, a membrane ; and phyllon, 

 a leaf. 



Sub-Order II. — OsmundacejB. 



Perns having the young fronds rolled up in a scroll- 

 like manner, the capsules clustered on the margin of 

 a transformed frond, and forming a panicle, without an 

 indusium ; destitute of a ring, and opening vertically by 

 two valves. 



17. OsMUNDA (riowering Fern). — Capsules clustered 

 into a branched panicle, terminating the frond. Name 

 apparently given from the Saxon words os, house, and 

 mund, peace. 



Sub-Order III. — Ophioglossace^. 



Ferns having their unfolded fronds straight and not 

 coiled, capsules arranged on a separate branch of the 

 frond, without a ring or indusium, coriaceous, and 

 opaque in texture. 



18. BoTRTCHiUM (Moonwort). — Capsules roundish, 

 sessile, clustered at the margin, and on one side of a 

 pinnated stalk. Name from the Greek, hotrys, a bunch 

 of grapes, from the appearance of the clusters. 



19. Ophioglossum (Adder's-tongue). — Capsules 

 1-celled, 2-valved, forming a compact two-ranked spike. 

 Name from the Greek, ophis, a serpent ; and glossa, a 

 tongue, from the resemblance of the fructification to 

 the tongue of a serpent. 



