ORDER 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. 

 Fructification 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, 1-celled, con- 

 taining numerous, minute spores. An- 

 theridia and pistillidia formed after ger- 

 mination, on tho young plant. (See figs. 

 491501.) 



Genera 200, specie* 2000. -r- A largo and in- 

 teresting order of flowerless plants, distin- 

 guished for their elegant, plume-like foliage. 

 They are usually a lew inches to a few feet 

 high, but sonic of the tropical species, as tho 

 Cyatheae of both Indies, are 1525 feet high, 

 Vicing with the palms in size and beauty. 



Properties. Generally mucilaginous nnd 

 mildly astringent, hence considered pectoral. 

 Aaplatam and Pteris are anthelmintic. Os- 

 mw.nda regalis has been successfully adminis- 

 tered for the rickets. 



Observation. The fructification of the ferns, 

 with its various appendages, is too minute to 

 be well observed by the naked eye ; but an 

 examination of it with the aid of a good lens 

 cannot fail to be interesting and satisfactory. 



7*) 



739 Polypodinm vulgare. 7D Frond. 741 

 Lobe of the frond enlarged, showing tho soi i. 

 742 One of the sori enlarged, showing the spor- 

 angia. 748 One sporange further magnified, 

 bursting and discharging the spores. 744 Soru3 

 of Aspidium marginnlo covered, with tho indu- 

 slum. 745 Same, side view. 



SUBORDERS AND GENERA. 



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



Fronds cauline, sereral, palmate (or radical and filiform), (b) 



Fronds all radical, clustered (never filiform), circinato in vernation. (2) 



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



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



not involved ; segments flat (c) 

 SUBORDER I. OPIIIOGLOSSE^E. (Sporangia naked, smooth, cartilaginous, 2-valvcd; noting.) 



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



a Fructification paniculate. Frond divided, fork-veined EOTRTCIIIUM. 2 



SUBORDER II. OSMUNDE^E. (Sporangia reticulate-roughened, papery, 2-valved, 



with no ring, spicate or paniculate.) b Fronds palmate. Climbing. LYGODICM. 3 



b Fronds filiform. Erect SCIIIZ.K. 4 



b Fronds 1 2-pinnatc OSMUNDA. 5 



SUBORDER III. POLYPODINEJL (Sporangia minute, on tho back of tho frond, 

 valveless, torn open by tho clastic ring which encircles it vertically.) 



C Sporangia scattered singly all over tho surface (not in sori), naked ACROSTICUM. (/ 



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

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



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



O Fronds sterile and fertile very different ; tho fertile spike-like STRUTIIIOPTEBIS. 8 



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



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



h. Indusiura continuous all around the segment PTERIS. 9 



h. Indusium from the apex of the segm. Midvein central CIIEILANTIIES. 10 



Midvein lateral or AniANTUM. It 



b. Indusium ft reflected tooth at the sinua between the segments DICKSONIA. 12 



