CULTIVATION. 865 



fbet, attaining the height of from eighteen to twenty 

 feet, growing only in damp places, generally gullies, 

 where the sun rarely penetrates, and where they are 

 sometimes covered with snow, and in summer the 

 atmosphere loaded with vapour. This suggests that, 

 with proper selection of situations, they might live 

 in the open air in the south and west of England, as 

 also the mild climate of Argyleshire, where shaded 

 ravines and gullies may be found similar to those of 

 Mount Wellington. 



"With few exceptions, Tree Ferns readily conform to 

 cultivation. A IsopMla capensis, A. excelsa, A. Australia, 

 Cyathea dealbata, G. medullaris, Dicltsonia antarctica, 

 and D. squarrosa, grow freely in the Temperate House ; 

 the lofty Alsophila glauca, the beautiful tessellated 

 stem of Cyathea arborea, with its crown of fine 

 fronds, and the broad shining fronds of Hemitelia 

 Jiorrida, assume a grand appearance in the Tropical 

 House. In general, the stems of Tree Ferns are of 

 sufficient size to warrant the name of trees ; but in 

 many the thickness is more apparent than real, the 

 diameter of the woody centre being often only a few 

 inches, but in many cases covered with successive 

 productions of out-growing aerial roots, which become 

 hard and wiry, and by their interlacing, form a com- 

 pact mass ; the points of these roots are, however, the 

 active feeders, and if a layer of fresh soil is occasion- 

 ally placed round the base of the stem, their growth 

 will be promoted, and vigour given to the plant. The 

 most fastidious Tree Fern to cultivate is Dicksonia 

 arborescens, a native of St. Helena. It was first intro- 

 duced to this country in 1 786, and many times since, 

 but refuses to become established, either in a tropical 



