24 
FERNS. 
[Polypodium. 
sums. C, front view of ditto. D, longitudinal section of leafstalk. G, transverse 
ditto. E, scalariform duct. F, vernation, rootstock, and roots. H, I, theca 
and spores. 
Sprengel enumerates no less than 250 species of this genus ; all of them are 
herbaceous, some a few inches only, and others several feet in height. Inhabitants 
of most parts of the world, particularly of the islands within the Tropics ; several 
are found on the continent of America, and a few are confined to China. Only 
four species are British.* 
1.— POLYPODIUM VULGARE. 
COMMON POLYPODY. POLYPODY OF THE OAK. WALL FERN. 
(Plate I, fig. 2.) 
Cha. — Leaf deeply pinnatifid, lanceolate. Lobes broadly linear, 
obtuse, somewhat serrated. Leaf-stalk smooth. Rootstock hairy. 
Syn. — Polypodium vulgarc, Tourn., Ger., Park., Rag, Linn., Huds., Lightf, 
Plum., Swz., Spreng., With., Smith, Hook., Mack., Gray, &c. — Ctenop- 
teris vulgaris, Newm., 1854. 
Fig. — E. B. 1149. — Flo. Dan. 1000. — Woodv.Med. Bot. supp. 271. — Ger. 467. 
— Bolt. 18. — Plu. Fil. t. A.f. 2. 
Des. — Rootstock creeping horizontally, at first covered with 
scales, and numerous stout, branched, hairy root-fibres. Leaf-stalk 
quite smooth, yellow, void of lobes half way up. Leaf from 6 to 
12 inches high, lanceolate, scarcely contracting below. Lobes 
broadly linear, obtuse, and slightly serrated, sometimes wanting 
the seri’atures, at others acuminate, wdiile occasionally they are 
found very much cut and divided. Sori naked, yellow, large, 
prominent, and arranged in straight lines equally distant from the 
margin and the midrib of the lobe ; each sorus terminating oue of 
the branches of a transverse vein. The plant is perennial, and the 
fruit found throughout the summer. 
/3. (P. Cambricum, Linn.) Leaf ovate ; pinnules ovate and deeply cleft. (A, B.) 
y. ( sinuatum .) Leaf ovate or triangular ; pinnules proliferous. (C, D.) 
S. ( serratum .) Pinnules distinctly and often doubly serrated, 
e. ( acutum .) Pinnules pointed ; leaves long ; both narrow'. (E.) 
9. ( bifidum .) Pinnules cleft at the point. (F.) 
Mr. Mackav remarks, in his ‘ Flora Ilibernica,’ that the Irish plant is some- 
what different from the Polyp. Cambricum of Linnaeus. It is in fact our variety y, 
which is the same as the Pol. Virginianum of Pursli, and intermediate between 
the usual state of the plant and the Cambricum ; it bears fruit copiously, whereas 
the real Cambricum is usually without fruit, both in its wild and cultivated state. 
Wc might expect this, indeed, from the feather-like appearance of the plant, and 
the dilatation of its lobes, a too great expansion of leaf being here as elsewhere 
detrimental to the production of fruit. The foregoing observation was made in 
distinct reference to a frond, of which C, in the annexed cut, is an exact repre- 
• The number of species In a genus is always subject to variation, particularly in one so 
extensive as Polypody, as newly-discovered plants are always adding to the number, while 
different classification often divides one genus into many. 
