258 BRITISH FERNS 



given above, the Bristle Fern, is due to the peculiarity that the 

 spore capsules are contained in little, urn-shaped vessels projecting 

 from the margins of the frond divisions, and through these urns 

 a vein is carried, and protrudes like a bristle from the orifice. Its 

 natural habitats here are by the sides of mountain streams, in the 

 vicinity, or actually in the spray of cascades, or in rocky hollows 

 where the air is constantly at saturation point and no sunshine 

 ever enters. T. radicans has a very tough, travelling rootstock, 

 which creeps over the rock surfaces and into their crevices, into 

 which the roots proper penetrate. The fronds, which are nearly 

 thrice divided, are of a deep, lucent green and translucent, but by 

 no means fragile. They are quite evergreen, and last for several 

 years. For the culture of this species we refer to our chapter on 

 Culture, under the head of Wardian Cases, since no Fern is better 

 adapted, or lends itself more admirably to case culture than this. 

 Several varieties have been found. 



Fig' 3 ! 7' &. v - Andrewsii. 



Andrewsii (Fig. 317). — Found in Ireland ; has narrower, more 

 lance-shaped fronds, with longer stalks and more widely separated 

 pinnae. 



Dilatatum. — A very handsome, broad-fronded form introduced 

 from Ireland by Messrs. Backhouse, of York. 



Proliferum. — A small-growing form, sent the writer many years 

 ago by Mr. Burbidge, of Dublin, as bearing bulbil plants on the 

 fronds, a la Asplenium bulbiferum. Young plants were raised from 

 these, but the parent eventually refused to develop more. 



Alatum. — Found in Ireland ; conspicuously winged stalks. 



Backhouseii. — Intermediate between dilatatum and Andrewsii. 



Crispum. — Found Killarney by Col. A. S. H. Lowe ; crispate and 

 irregularly branched. 



Dissectum. — Finely cut, beautiful form. 



