
THE BRITISH FERNS. 
THE LIMESTONE POLYPODY. 
POLYPODIUM ROBERTIANUM. 
P. fronds erect, rigid, glandulose, pentangular deltoid, subternate ; 
lower branches (or pinne) bipinnate, stalked, their pinnulets or 
lobulets oblong obtuse, crenate or nearly entire; stipes glandulose. 
[Plate XII. ] 
POLYPODIUM ROBERTIANUM, Hoffmann, Deutschl. Fl. ii. in addenda to p. 10 
(1795). Fries, Sum. Veg. 82. Koch, Synops. 2 ed. 974. Nyman, Syll. Fl. 
Europ. 430. Moore, Handb. Brit. Ferns, 3 ed. 66; Id., Ferns of Gt. Brit. 
and Ireland, Nature Printed, t. 6. Babington, Man. Brit. Bot. 4 ed. 420. 
Lowe, Nat. Hist. Ferns, i. t. 28. 
POLYPODIUM CALCAREUM, Smith, Fl. Brit. 1117 (1804) ; Id., Eng. Bot. xxii. 
t. 1525 ; Id., Eng. Fl. 2 ed. iv. 270. Deakin, Florigr. Brit. iv. 43, fig. 1582. 
Hooker & Arnott, Brit. Fl. 7 ed. 582. Newman, Hist. Brit. Ferns, 2 ed. 
131. Sowerby, Ferns of Gt. Brit. 12, t. 4. Willdenow, Sp. Plant. v. 210. 
Sprengel, Syst. Veg. iv. 60. Presl, Tent. Pier. 180. 
PoLYPODIUM DRYOPTERIS, VAR., Bolton, Fil. Brit. 53, t. 1. Bentham, Handb. 
Brit. Fl. 627. s 
POLYPODIUM DRYOPTERIS, B. MINUS, De Candolle, Fl. Franç. ii. 565. 
POLYPODIUM DRYOPTERIS, 8. ROBERTIANUM, Ruprecht, Dist. Crypt. Vasc. Ross. 
52. Ledebowr, Fl. Ross. iv. 509. 
PoLYPODIUM DRYOPTERIS, v. CALCAREUM, Gray, Man. Bot. North. U. States, 590. 
NEPHRODIUM DRYOPTERIS, Michaux, Fl. Bor. Amer. ii. 270. 
LASTREA CALCAREA, Bory, Dict. Class. @ Hist. Nat. ix. 233. Newman, Nat. 
Alm. 1844, 17. i 
LASTREA ROBERTIANA, Newman, Hist. Brit. Ferns, 2 ed. 18. 
PHEGOPTERIS CALCAREA, Fee, Gen. Fil. 243. J. Smith, Cat. Cult. Ferns, 17. 
GYMNOCARPIUM ROBERTIANUM, Newman, Phytol. iv. 371; Id., Appendix, 
1851, xxiv.; Id., Hist. Brit. Ferns, 3 ed. 63. 

Caudex creeping extensively, branched, thicker than a straw, 
dark-brown, scaly. Scales pale-brown, semitransparent, lanceolate. 
Fibres dark-brown, branched, clothed with a brighter brown 
pubescence. 
Vernation circinate ; the pinnules rolled up separately into little 
globules, the pinne then rolled each separate inwards towards the 
main rachis, which is next itself coiled up. 
Stipes longer than the frond, often twice as long, stoutish, succu- 
lent when young, becoming stiff and erect, abundantly scaly about 

