132 THE BOOK OF CHOICE FERNS. 



Ferns, t. 4. Nicholson, Dictionary of Gardening, iii., p. 189. Lowe, Our 

 Native Ferns, i., t. 4. Eaton, Ferns of North America, i., t. 21. Beddome, 

 Ferns of British India, t. 74. Druery, Choice British Ferns, p. 117. 



In planting the Oak Fern, a spot where moisture and shade can always 

 be depended upon should, if possible, be selected, and a shallow bed made of 

 a compost of two parts of fibrous peat, one part of leaf mould, and a free 

 admixture of silver sand, or, better still, of broken sandstone. If grown in 

 pots for a cool frame or for the greenhouse, where it makes most pleasing 

 objects, the above mixture will be found equally suitable ; but in either case 

 avoid putting in too much soil ; a depth of Sin. to 4in. is quite sufficient. It 

 is also indispensable that thorough drainage should be secured, for water 

 remaining stagnant about its roots is very injurious to P. Dryopteris. In 

 planting, great care must also be taken to prevent the rhizomes from being 

 buried too deeply, in which case they seldom grow ; they must be kept 

 only just below the surface of the soil, through which it is advisable to 

 allow the tips to protrude. Planting should take place about April, 

 and a moderate watering must follow, after which the soil requires to be 

 kept constantly moist. Although totally deprived of foliage during four or 

 five months of the year, the Oak Fern should never be allowed to get dry at 

 the roots, for the rhizomes soon shrivel up and the spring growth then only 

 produces small or deformed fronds, as the plants are much weakened. It is 

 also advisable to give plants grown in pots a slight covering during the 

 winter, though they do not require this attention when planted out. 



This species, readily increased by division, does not appear to have 

 produced any constant variations ; several more or less curious forms of it 

 have from time to time been noticed, but none of them have remained 

 constant under cultivation. 



P. (Cyrtomiphlebium) dubium — Cyr-tom-iph-leb'-i-um ; duV-i-um 

 (doubtful), Hooher. 

 This stove species, native of the Andes of Ecuador and Peru, is exceedingly 

 like some of the forms of Aspidium {Cyrtomium) falcatum in habit and texture. 

 Its fronds, borne on strong, tufted stalks 1ft. to IJft. long and densely scaly 

 throughout their length, are 2ft. to 3ft. long, 6in. to 12in. broad, with unequal- 

 sided leaflets Sin. to 6in. long, terminating in a sharp point and finely 



