1032 THE FERN FAMILY. 



there is nothing in habit to serve as a guide, and the indusium of the 

 two latter genera is often so evanescent that it requires the most care- 

 ful examination of specimens, in exactly the proper state, to ascertain 

 its existence. I have been induced, therefore, with a view to assist the 

 beginner in the determination of the British species, to include in the 

 following Table of Genera the species also of the most difficult ones, 

 endeavouring to lead to them by more prominent characters, without 

 reference to the more minute, although essential ones, which distinguish 

 the genera. It must be recollected, however, that to determine Ferns 

 they must be in fruit. It is hopeless to attempt to find out by books 

 to what species a barren frond belongs, and monstrous developments, 

 and deformed fronds, now not uncommon in cultivation, and found 

 occasionally wild, are here wholly passed over.* 



{Fructification in a terminal spike or panicle. The frond either leaf- 

 like, or bearing a leaf in the lower part 2 

 Fructification in a little cup or involucre at the edge of the frond . . 4 

 Fructification on the back or under side of some or all the fronds . . 5 

 {Fronds twice pinnate, usually 2 or more feet high, the fructification 

 forming a panicle at their extremity 3. Osmund. 

 Frond stem-like, not 6 inches high, with a terminal spike or 

 panicle 3 



„ f Spike simple. Leaf entire 1. Adder's-tongue. 



I Spike branched into a panicle. Leaf pinnate .... 2. Moon wort. 



{Fronds numerous, scarcely 2 inches high, pinnate, with few deeply- 

 lobed segments. Involucre ovate, 2 lobed . . 17. Hymenophyll. 

 Fronds 6 or 8 inches high, 2 or 3 times pinnate, with crowded seg- 

 ments. Involucres cup-shaped 16. Trichomanes. 



f Fronds tufted, of 2 sorts, the central ones erect, fruiting, the outer 



5 { ones barren, usually shorter, with broader lobes 6 



^Fruiting and barren fronds similar or nearly so 8 



{Fronds (stiff) simply pinnate, with entire lobes, the fruiting linear, the 

 barren lanceolate 11. Blechnum. 

 Fronds (delicate) much divided, with small, ovate or oblong, toothed 

 lobes 7 



,_ f Sori forming a line close to the margin of the frond . 5. Allosorus. 

 I Sori oblong, scattered on. the surface of the frond . . 6. Gytmnogram. 

 f Fructification concealed by, or intermixed with chaffy scales or hairs . 9 

 j Fructification in lines along the margin of the fronds, the indusium a 



8 <{ membrane attached to the margin 10 



I Fructification in circular, oblong, or linear sori, on the under surface, 

 L without chaffy scales 11 



* Further details of this beautiful tribe of plants may be found in the numerous 

 illustrated works on Ferns which are daily advertised, among which Sir W. J. 

 Hooker's beautifully illustrated volume, ' British Ferns and their Allies,' is the most 

 recently published and most complete. 



