On the British species of Polypodiwm. 145 



Division A. — Root creeping. 



1. P. vulgare, Linnaeus. 



This species is abundant in every part of the kingdom that 

 I have visited ; there is scarcely a hedge-row without it. — 

 Generally speaking, it is but little subject to variation; it 

 however assumes the following forms. 



a. vulgare. Pinnatifid, lobes simple. 



(3. serratum. Pinnatifid, lobes deeply serrated. 



y. Cambricum. Pinnatifid, lobes deeply indented. 



o. proliferum. Pinnatifid, lobes broadly and deeply indented, almost 

 twice pinnatifid. 



e. digitatum, (n. v.) Pinnatifid, lobes with the extremities divided. 



£. acutum. Pinnatifid, lobes terminating in a sharp point. 



2. P. Phegopteris. Frond triangular, drooping, pinnate ; pinnce pinnati- 

 fid, opposite, the first pair turned back ; sori marginal. 



3. P. Dryopteris. Frond triangular and triple, i. e. at its first division 

 forming three nearly equal sub-divisions; each of these twice pinnate.. So- 

 ri near the margin, scattered. 



This beautiful and delicate little fern is found in the crevi- 

 ces of rocks, mostly in the neighbourhood of waterfalls, but 

 almost invariably sheltered from their spray, by a projecting 

 ledge. Two varieties have been named. 

 a. Dryopteris. As above. 



/3. calcarcum. As above, but is said to possess larger sori, and to be 

 of a darker green colour. 



4. P. Thelypteris. Frond pinnate, pinnce somewhat distant, deeply pin- 

 natifid ; sori regular, almost marginal, when immature separate, when ma- 

 ture, so crowded as to form a nearly continuous marginal line. 



No varieties of this beautiful species have received names. 

 The barren fronds differ from the fertile ones, in having their 

 pinnce and lobes broader and more crowded. 



Note. The ferns of this division are to be instantly distin- 

 guished from those which follow, by their mode of growth ; 

 the roots send out horizontal runners, which, at certain knots, 

 issue fresh fibres, fix themselves, and become plants. They 

 are never fast in the earth like those which follow. 

 Division B. — Root tufted. 



5. P. Oreopteris. Frond pinnate, pinnce cleft, decreasing in size as they 

 approach the root, until they become very short ; lobes rounded, sori mar- 

 ginal ; whole plant covered with glands, containing a powerfully scented 

 liquid. 



This very distinct fern covers acres of waste mountain in 

 the neighbourhood of ' Water-break-its-neck,' Radnorshire; 

 and takes the place of Filia? mas in most of the hedge-rows 

 of that county. Its varieties are un-named. 



6. P. cristatum. Frond pinnate, pinna distant, opposite, pinnatifid, 

 short, obtuse ; sori discoidal. 



I have not seen this species growing ; the dried specimens 

 in herbaria appear distinct from the following. 



m 2 



