232 



Commercial Gardening 



P. serrulata and its varieties, recognized by having winged rachises, 

 are also popular market Ferns, and sell in all sizes, those in 5-in. pots 

 being most in demand. 



P. tremula the "Trembling Fern" of Australia a vigorous species 

 with fronds 1-3 ft. long and four-times pinnate, is a fine market Bracken, 

 and chiefly sells in 5-in. and 6-in. pots. There are several forms of it, 

 the best being flaccida and Smithiana, densely crested. Other good 

 market Pterises are P. arguta, P. biaurita, and its varieties argentea and 

 nemoralis-, P. hastata, and P. straminea. 



Scolopendrium. The best-known member of the genus, and the one 

 having the greatest commercial value, is the common Hart's Tongue Fern 



(S. vulgare). The typical species 

 is found growing wild in the 

 copses and hedgebanks, and be- 

 tween rocks, in many parts of 

 the British Islands, and is also 

 distributed over North Africa, 

 West Asia, Japan, and North- 

 west America. It has short 

 stoutish rootstocks, and tufts 

 of strap - shaped, bright -green 

 leathery fronds 6 to 18 in. long. 

 The "sori", or clusters of spore 

 cases, are arranged in streaks 

 almost at right angles to the 

 midrib, but vary considerably in 

 length and number. There are 

 now almost innumerable varieties 

 in cultivation, one hundred or 

 more of which have been regarded 



as first-class garden plants by experts. The variations consist chiefly in 

 the extraordinary way in which the simple fronds of the type have been 

 modified into all kinds of shapes by cresting and laceration. Many of these 

 varieties, it must be admitted, are mere vegetable monstrosities, curious 

 rather than beautiful, but others are very ornamental in appearance. 



The Hart's Tongue Ferns are now largely used for planting in moist 

 and shady parts of the rock garden and flower border, or beneath over- 

 hanging trees and shrubs. They are all quite hardy, and flourish in sandy 

 loam, peat, and leaf soil in about equal proportions. They are also excellent 

 subjects for growing in cold greenhouses without any heat whatever. 



A very curious species is S. rhizophyllum, the "Walking Fern" of 

 North America (fig. 315). The simple fronds taper to a point and have a 

 pair of rounded auricles at the base, while new plantlets are developed at 

 the tips of the fronds under favourable conditions. It is practically hardy 

 in most parts of the kingdom. 



Selaginella. Although belonging to a quite different family (the 



Fig. 315. Scolopendrium rhizophyllum 



