372 THE PRINCIPLES OF FLORICULTURE 



species, but a night temperature of 55 to 60 best suits 

 them. 



598. Polystichum (commonly called Aspidium), botani- 

 cal classification. Order, Polypodiacese ; genus, Polys- 

 tichum (Greek, many rows, referring to the sori) ; 

 species : setosum and coriaceum. Many of the species have 

 a densely setose stem, especially near the base. There are 

 several native species, the best known of which is P. 

 acrostichoides, the Christmas fern. 



599. Polystichum, botanical characters. Polystichum 

 is a genus of ferns having rather coarse, leathery fronds. 

 The sori are rounded and covered by a peltate indusium 

 which is attached by a stalk to the central vein. They 

 are easily grown and thrive best in shade. Most species 

 are adapted for growth in living-rooms and make excellent 

 house plants. When young, they are excellent for fern 

 dishes. 



Habitat. Europe. 



The culture is similar to pteris. 



600. Holly ferns, botanical classification. Order, 

 Polypodiacese ; genus, Cyrtomium (Greek, a bow, referring 

 to. the curved character of the sori) ; species : falcatum, 

 caryotideum, and its variety Rochfordianum, and Fortunei. 



601. Holly ferns, botanical characters. The holly fern 

 has once pinnate fronds, the pinnae with entire or deeply- 

 toothed margins. The texture of the frond is heavy, 

 leathery and very shiny. The round fruit dots are 

 variously scattered over the back of the pinnae. The 

 base of the stipe is more or less densely coated with sete. 



Habitat. Asia. 



602. Culture. The holly fern group contains very 

 valuable commercial plants. They are easily grown, and 

 because of the dark green, glossy character of the foliage, 



