190 PHYSIOGNOMY OF PLANTS. 



sea and the plains ; and hence, besides great equality of tem- 

 perature, it also enjoys uninterruptedly a high degree of 

 humidity. (Robert Brown, in Appendix to Expedition to 

 Congo, p. 423.) The inhabitants, who are of Spanish de- 

 scent, call this zone " tierra templada de los helechos." The 

 Arabic word for fern is feledschun, f being changed into /* 

 in helechos according to Spanish custom : perhaps the Arabic 

 feledschun is connected with " faladscha," " it divides " in 

 allusion to the finely divided margins of fern leaves or fronds. 

 (Abu Zacaria Ebn el Awam, Libro de Agricultura, traducido 

 por J. A. Banqueri, T. ii. Madr. 1802, p. 736.) 



The conditions of mild temperature and an atmosphere 

 nearly saturated with vapour, together with great equability 

 of climate in respect to both temperature and moisture, are 

 fulfilled on the declivities of the mountains, in the valleys of 

 the Andes, and above all in the mild and huiriid atmosphere 

 of the southern hemisphere, where arborescent ferns extend 

 not only to New Zealand and Yan Diemen Island (Tasmania), 

 but even to the Straits of Magellan and to Campbell Islands, 

 or to a latitude almost corresponding to that of Berlin in the 

 northern hemisphere. Of tree-ferns, Dicksonia squarrosa 

 grows vigorously in 46 South latitude, in Dusky Bay (New 

 Zealand) ; D. antarctica of Labillardiere in Tasmania j a 

 Thyrsopteris in Juan Fernandez ; an undescribed Dicksonia 

 with stems from 12 to 15 (nearly 13 to 16 English) feet in 

 the south of Chili, not far from Yaldivia ; and a Lomaria 

 of rather less height in the Straits of Magellan. Campbell 

 Island is still nearer to the south pole, in 52J lat., and 

 even there the stem of the Aspidium venustum rises to 



