Ophioglossum.] XCIV. FILICES. 557 



f No scarious scales on the stalk. No glands on the leafy part. 



J 7 (3). ASPIDIUM Thelypteris. 



1 Stalk with brown scarious scales at the base. Minute glands on the under surface 



V. of the segments 7 (4). Aspidium Oreopteris. 



( Segments of the pinnas oblong, very numerous, scarcely broader at the base. 

 23 \ 7 (5). ASPIDIUM Filix-mas. 



{ Segments ovate, wedge-shaped at the base . . 7 (6). Aspidium cristatMm. 



? Segments of the pinnas with finely pointed almost prickly teeth ; the inner lobe 

 9 . J or tooth at the base much larger than the rest 7 (2). Aspidium aculeatum. 



1 Segments of the pinnas with shortly pointed teeth or pinnatifid, the lobes of each 



(^ side similar . 25 



f Sori circular. No indusium 4 (3). Polypodium alpestre. 



A Sori circular, with a kidney-shaped or almost peltate indusium attached by a 

 Zb ) point 26 



V Sori rather oblong, with an indusium attached along one side 8. Asplenium. 



( Segments ovate or ovate-lanceolate. Indusia conspicuous and persistent. 

 26 < 7 (6). Aspidium cristatum. 



( Segments oblong-lanceolate 27 



97 / Indusia conspicuous and persistent .... 7 (8). Aspidium rigidum. 



\ Indusia small and often soon disappearing . 7(7). Aspidium spinulosum. 



I. OPHIOGLOSSUM. ADDER'S TONGUE. 



Stem simple, bearing a single leaf-like barren frond in the lower 

 part, and a simple terminal fruiting spike. Spore-cases rather large, 

 closely sessile, in two opposite rows, each opening by a transverse 

 fissure. 



A genus of very few species, but widely distributed over most parts 

 of the globe. 



1. O. vulgatum, Linn. (fig. 1278). Adder 's-tongue. — Rootstock very 

 small, but apparently perennial. Stem (combined stipes of the barren 

 and fertile frond) solitary, from a few inches to near a foot high, with 

 an ovate or oblong entire leaf -like barren frond, usually 2 to 3 inches 

 long, narrowed at the base into a shortly sheathing footstalk, and 

 usually attached below the middle of the stem. Spike terminal, J to 

 about an inch long, bearing on each side from about 15 to 25 closely 

 sessile spore-cases. 



In moist meadows, and pastures, throughout Europe, Asia, except 

 the extreme north, North America, and apparently also in the southern 

 hemisphere as well as within the tropics. Generally distributed over 

 Britain, but more common in some parts of England and in Ireland 

 than in the north of Scotland. Fr. summer. 0. lusitanicum, Linn., is 

 now believed to be a mere variety, only differing from the common 

 form in its small size, the slender stems varying from 1 to 3 inches, 

 the leaf or barren frond linear or lanceolate, narrowed into a stalk, and 

 seldom above 1J inches long. It is usually to be found only in winter 

 near the sea, along the west coast of Europe to Guernsey, but not on 

 the main British Isles. 



II. BOTRYCHIUM. MOONWORT. 



Stem of Ophioglossum, but the leaf -like barren frond is divided, the 

 terminal spike is branched, forming a panicle, and the spore-cases are 

 globular, and, although sessile, quite distinct. 



A small genus, distributed over the temperate regions of the northern 

 hemisphere, and more sparingly in the southern one. 



