TREE-FERNS. 



127 



duce its height. Select a time when the fronds 

 have attained their full growth, and are dormant : 

 then cut the trunk off, so that, when the upper 

 part is again planted, it will be of the required 

 altitude. By careful tending, the fern will, in a 

 year or two, be in good order again, and ready to 

 continue its growth undisturbed for perhaps twenty 

 years. 



Small plants, and occasionally large ones, of 

 many of the choice varieties of arborescent ferns, 

 may be obtained of the larger plant-dealers in 

 this country. 



The Tree-Ferns belong to several genera, and 

 have many very near relatives among the low- 

 growing species. Thus the Dicksonia antarctica 

 (PI. 7), one of the largest among the Tree-Ferns, 

 has associated with it in the same genus D. pttnc- 

 tilohida, one of our commonest native ferns, with a 

 creeping stem, and with the whole plant rarely 

 reaching three feet in height. The Blechnum 

 Brasiliense {see frontispiece) has among its con- 

 geners species which are seldom more than six 

 inches high. 



Williams, in "Select Ferns," gives a list of forty 

 Tree-Ferns which have been successfully grown in 

 the greenhouses of England, so arranged as to 

 show the species which require a temperature 

 averaging 70° Fah. in summer and 42° in winter, 

 and those whose average summer temperature 



