48 ENGLISH BOTANY. 



rich vivid green, but not at all shining. In exposed places they 

 frequently become tinged with red. They are very delicate in texture, 

 and soon wither if after being gathered they are exposed to the air. 

 Properly speaking, this Fern produces no barren fronds distinct 

 from the fertile ones; still we frequently meet with fronds fully 

 developed without sori. These have the pinnae broader and ultimate 

 pinnae more approximate, and a greater number of them combined 

 than the fertile fronds, so that they appear to be less divided, but 

 they occur too rarely to be considered more than an accidental 

 variation. 



Oak-fern. ■ 



SPECIES II.-PH EG OPTERIS ROBERTIANA. A. Braun. 



Plate 1846. 

 Babenli, Crypt. Vase. Exsicc. No. 58. 

 Ph. calcarea, Fee, Gen. Fil. p. 243. Babenk I.e. 

 Polypodium Eobertianum, Hoffm. Bab. Man. Brit. Bot. eel. vii. p. 445. Hook. fil. Stud. 



Fl. p. 467. Moore, Nat. Print. Brit. Ferns, 8vo. ed. Vol. I. p. 92. Koch, Syn. Fl. 



Germ, et Helv. p. 974. Fries, Summ. Veg. Scand. p. 82. 

 Polypodium calcareum, Sm. Engl. Bot. No. 1525 ; and Eng. Fl. Vol. IV. p. 283. 

 Polypodium Dryopteris, (3. Eobertianum, Buprecht. Led. Fl. Boss. Vol. IV. p. 509. 



Hook. & Bak. Syn. Fil. ed. ii. p. 309. 

 Polypodium Dryopteris, /?. calcareum, Gr. & Godr. Fl. de Fr. Vol. III. p. 628. 

 Lastrea Kobertiana, Newm. Hist. Brit. Ferns, ed. ii. p. 13. 

 Lastrea calcarea, Bory, Diet. Class. Hist. Nat. Vol. IX. p. 233. 

 Gymnocarpium Eobertianum, Neiom. Phyt. 1851, p. 371, and App. 24 ; and Brit. Ferns, 



ed. iii. p. 63. 



Caudex elongate, slender, wiry, tortuous, creeping, branched, 

 flocculently tomentose, the younger part thickly clothed with ovate 

 scales, producing fronds at rather short intervals. Fronds all similar. 

 Stipes erect, wiry, longer than the lamina, minutely glandular, at 

 first with numerous ovate or lanceolate often piliferous pale scales, 

 ultimately naked. Lamina curved backwards, firm, dull greyish- 

 green, sprinkled with very minute stalked glands, which are most 

 numerous on the rachis partial rachides and mid-veins, deltoid or 

 triangular-deltoid, bipinnate , acuminate, and very acute ; ultimate 

 pinnules or segments often convex with reflexed margins, oblong, 

 obtuse, crenate or entire. Sori round, arranged in a line near the 

 margin on each side of the pinnules or ultimate segments, attached 

 to the lateral veins a little below their apex. 



On limestone rocks, local. It occurs in Somersetshire, Wiltshire, 

 Oxford, Bucks, Gloucester, Hereford, Stafford, Salop, Glamorgan, 

 Brecon, Denbigh, Derby, Lancaster, York, Durham. Besides these 



