CYSTOPTERIS. 



97 



fleshy bases of the old stalks. In mature plants they are usually Gin. to 

 12in. long and Sin. to 4in. broad at their widest part ; but Prof. F. L. Harvey 

 mentions fronds measuring, with their stalks, fully 4ft. in length. They are 

 usually lanceolate (spear-shaped) frequently much elongated upwards, and bi- or 

 tripinnatifid (twice or three times divided half-way to the midrib) ; their 

 broadest part is at the base, where the leaflets are often 2in, to Sin. long, 

 lin. broad, and divided into narrow-oblong segments cut down nearly to the 

 midrib and slightly toothed ; thence they gradually narrow to their extremity, 

 having, according to Eaton, a narrower and more tapering outline than any 

 other known North American Fern with compound and feathery fronds. The 

 stipes (stalks) are usually 4in. to 6in. long, very slender, smooth, and of 

 a brittle nature, usually green, except at the base, where they are dark brown ; 

 but sometimes the whole stalk and rachis (stalk of the leafy portion) are 

 brownish to the very extremity of the frond. The sori (spore masses) are 

 produced so abundantly as to be found on all portions of the frond, even to 

 the base ; they are disposed two to twelve to a pinnule and usually in two 

 rows, one in each segment. The bulbils, by which this species is readily 

 distinguished from all others and by means of which it is easily propagated, 

 are usually found on the under-side of the fronds, mostly at the base of the 

 leaflets, but they often occur in various positions. They consist of two 

 — sometimes three, and even four — rounded, fleshy, cotyledon-like, greenish or 

 deep-coloured masses containing a rudimentary frond or two between their 

 bases. It is somewhat surprising that such an elegant species, perfectly hardy 

 and so prone to reproducing itself by both its bulbils and its spores, should 

 not have become naturalised in England. According to Lowe, it was intro- 

 duced in 1648 by Mr. Tradescant, who then sent it to the Royal Gardens, 

 Kew. — Hooker^ Species Filimm^ i., p. 199. Nicholson^ Dictionary of Gardening^ 

 i., p. 429. Eaton, Ferns of North America, ii., t. 53, Lowe, Ferns British 

 and Exotic, vii,, t, 36. 



C. fragilis — frag'-il-is (fragile), Bernhardi. 



This is probably the commonest of the known species of Cystopteris, and 

 it possesses a peculiarly cosmopolitan character ; for, besides being a thoroughly 

 British Fern, it is found in all parts of Europe and Asia, everywhere from 

 Iceland to Kamtcshatka ; from the Arctic regions to Madeira and the Himalayas, 



VOL. II. II 



