332 



THE BOOK OF CHOICE FERNS. 



furnislied with flabellato-pinnatifid piiina3 (leaflets somewhat fan-shaped and 

 divided nearly to the midrib on their upper side). The sori (spore masses), 

 which are stalkless and usually solitary in the axils of the narrow segments, 

 are provided with a nearly round, two-valved involucre (covering) that is 

 copiously toothed on the upper margin. — Hooker^ Species Filicum, i., p. 95. 

 Lowe, Ferns British and Exotic, viii., t. 5b ; Our Native Ferns, ii., t. 72. 

 Beddome, Ferns of Southern India, t. 265. 



However spreading and flourishing we meet with the Tunbridge Wells 

 Filmy Fern in its native state, often covering large surfaces of rock and stone 

 exposed to the action of all kinds of weather, we find, when an attempt at 

 cultivation is made, that it is one of the most difficult of all Hymenophyllums 

 to manage. It dislikes water over the fronds, and thrives well either in 

 a mixture of equal parts of peat and silver sand or on a block of sandstone, 

 the principal object being to have it pressed hard on to the material upon 

 which it is intended to grow. Dr. John Winter, of Brighton, a most successful 

 cultivator of these plants, says that the treatment which gives the most 

 satisfactory results consists in laying the sheet of Hymenophyllum upon 

 a porous piece of stone without any soil, and laying a slab over it, leaving it 

 in that state for three to four weeks, after which time the plant has usually 

 taken hold of the new stone, when the slab is removed. 



H. undulatum — un-dul-a'-tum (wavy). Smith. 



A pretty species, native of Mexico, Jamaica, and Peru, with narrow- oblong, 

 pendent fronds of a flaccid natm^e, oin. to 6in. long, scarcely lin. broad, three 

 times divided nearly to the midrib, and borne on very slender stalks lin. to 

 2in. long. The sori (spore masses), two to six to a leaflet, are provided with 

 an involucre (covering) that is di^dded nearly to the base and has rounded 

 valves slightly crisped towards the margin, but not toothed. — Hooker, Species 

 Filicum, i., p. 105. 



H, unilaterale — u-nil-at-er-a'-le (one-sided), Bory. 



Although closely related to H. tunhridgense, this plant, popularly known 

 as "Wilson's Filmy Fern," is sufficiently distinct to be separated from that 

 species. It is equally of a cosmopolitan character, being found in a natural 

 state in l^orway, in South Africa, in the Falkland Islands, in Tasmania and 



