POLYPODIUM. 



205 



colour, two very distinct forms of fronds. The barren ones, 4in. to Bin. 

 long and 2in. broad, are cut down three -quarters of the way to the rachis into 

 blunt lobes, while the fertile ones, l^ft. to 2ft. long, 6in. to Sin. broad, and 

 distinctly stalked, have blunt, entire lobes 2in. to 3in. long, Jin. broad, reaching 

 down nearly or quite to the rachis. Both kinds are of a soft, papery texture, 

 and their spore masses are disposed in a single row on each side of and close 

 to the midrib. Fig. 58 is reduced from Col. Beddome's " Ferns of British 

 India," by the kind permission of the author. — Hooker, Synopsis Filicum, 

 p. 367. Beddome, Ferns of British India, t. 216. 



P. (Phegopteris) Robertianum — Phe-gop'-ter-is ; Ro-ber-ti-a'-num 

 (Robert's), Hoffmann. 

 This distinct and pretty, hardy Fern, popularly known as the " Limestone 

 Polypody," " Smith's Polypody," and the " Rigid Three-branched Polypody," 

 was formerly, and is now by some authors, looked upon as a variety of 

 P. Dryopteris. Bolton was the first to point out the difference between 

 P. Robertianum and P. Dryopteris, and Hoffmann to pronounce it a distinct 

 species, which T. Moore and Lindley have retained. It is of very similar 

 appearance, though a much larger and more robust Fern, and its fronds are 

 covered with a down that gives it the appearance of being dusted over with 

 lime. Another specially distinct character resides in the development of its 

 fronds, which never assume the appearance of three little balls like those of 

 P. Dryopteris, and, contrary to that popular species, P. Robertianum seems 

 to delight in sunshine. It is a native of England, Wales, France, Hungary, 

 Germany, Switzerland, Canada, Norway, and Asia, and is found in a wild 

 state only on limestone soil, though, under cultivation, it thrives in light soil 

 without additional limestone. Its natural presence in any part of Ireland has 

 not until now been recorded, and, although, generally speaking, it is a North- 

 of- England Fern, it has not been discovered in Scotland and has only seldom 

 been found in Wales (principally in Denbighshire). T. Moore, in " Ferns of 

 Great Britain and Ireland," remarks that in the West of England it only 

 descends to 250ft. above the sea, and in the North it ascends to 900ft. Lowe 

 also states that Dr. Hooker found it on the Himalayas at elevations of from 

 5000ft. to 8000ft. In England it has been gathered about Matlock Bath and 

 on the roadside under the Lover's Leap, at Buxton, in Derbyshire ; near 



