Oeder 160.— FILICES. 



815 



Order CLX. FILICES. Ferns. 



Stem a perennial, creeping, horizontal 

 rhizome, or sometimes erect and arbores- 

 cent Fronds (fruit-bearing leaves) va- 

 riously divided, rarely entire, with forked 

 veins, and mostly circinate vernation. 

 Fruciificaiion occupying the back or mar- 

 gin of the fronds, arising from the veins. 

 Sporangia (spore-cases) of one kind, scat- 

 tered or clustered in sori, l-celled, con- 

 taining numerous, minute spores. Ari- 

 theridia and pistillidia formed after ger- 

 mination, on tho young plant. (See figs. 

 491—501.) 



Genera 200, specieii 2000. — A Large and in- 

 teresting order of floworli'ss plants, distin- 

 guished for their elegant, plume-like foliage. 

 They are usuMlly a i'e^v inches to a few feet 

 high, but some of tlie tropical species, as tho 

 Cyatheffi of both Indies, are 15—25 feet high, 

 vicing with the palms in size and beauty, 



Propertieft. — Geuprnlly mucilaginous and 

 mildly astringent, licnco con.sidereil pectoral. 

 Aspiclium and Pteris are nnthelinintic. Os- 

 munda regalis has been successfully adminis- 

 tered for the rickets. 



Ohs6r-vniio7t. — The fructiii cation of the ferns, 

 with its various appendages, is too minute to 

 be well observed by the naked eye ; but an 

 oxamination of it with the aid of a good lens 

 cannot fail to bo Interesting and satisfactory. 



739 Polypodium vnlgare. TiO Frond, 741 

 Lobe of the frond enlarged, showing tho eorl. 

 742 One of the sori enlarged, showing tho spor- 

 angia. 748 One sporange further magnified, 

 bursting and discharging the spores. 744 Borua 

 of Aspidium marginalo covered with the indu- 

 sium. 745 Same, side view. 



SUBORDERS AND GENERA. 



§ Frond catiline, solitary, straight in vernation. Stem erect, (a) 



§ Fronds caulino, several, palmate (or radical and filiform), (b) 



S Fronds all radical, cl-ustered (never filiform), circinato in vernation. (2) 



2 Sporangia spiked or panicled, naked (not involved in revolute fronds), (b) 



2 Sporangia on the back of tho fronds,— but involved in the revolute segm Nos. 8, 10 



" — not involved ; segments flat, (c) 

 Sfbobder I. OPHIOGLOSSEjE. (Sporangianaked, smooth, cartilaginous, 2-valved; noting.) 



a Fructification spicate. Frond entire, reticulate-veined OpmoGLOSsuM. 1 



a Fructification paniculate. Frond divided, fork-veined BoTEYCniirM. 3 



Sttbohdeb II. OSMUNDEjE, (Sporangia reticulate-roughened, papery, 2-valved, 



with no ring, spicate or paniculate.) — b Fronds palmate. Climbing. LYGODnTM. S 



— b Fronds filiform. Erect Scinz^. 4 



— b Fronds 1 — 2- pinnate OsjiuNnA. C 



SuBOEDKB III. POLTPODINEJE. (Sporangia minnte, on tho back of tho frond, 

 valvelcss, torn open by the elastic ring which encircles it verticall3\) 



C Sporangia scattered singly all over the surface (not in sori), naked Acrosticum. 6 



C Sporangia collected in dots (sori) springing from tho veins, (d) 

 d Fruit-dots naked, having no indusium (special covering), (e) 



e Fronds all alike, flat. Fruit-dots orbicular Polypodium. 7 



G Fronds sterile and fertile very different; the fertile spike-like Steutuiopteeis. 8 



d Fruit-dots invested with special coverings (indusia). (g) 



g Fruit-dots marginal ; indusium a narrow, reflected edge of frond, (h) , 



h Indusium continuous all around the segment Pteris. 9 



h. Indusium from the apex of the segm. — Midvein central CnBiLANniEs. 10 



— Midvein lateral or Adiahtum. 11 



h Indusium a reflected tooth at the sinus between the segments Bicesonia. 12 



