TREE FERNS. 



Tree ferns are characteristically inhabitants cf wet, 

 forested, tropical and subtropical regions and reach 

 their best development in mountainous districts which 

 are not subject to drouth or pronounced seasonal 

 change. In the Greater Antilles they are found mainly 

 on the northern slopes and summits of the higher 

 mountains, as for .example, the Sierra Luquillo of 

 Porto Rico and the Blue Mountains of Jamaica, where 

 the cool moisture-laden trade-winds from the north- 

 east bring an ample supply of moisture. The fern 

 vegetation to the south of these mountains is more or 

 less strongly xerophytic both islands mentioned even 

 having a semi-arid region of cactus and scrub growth. 

 Similar conditions were noted on the Sierra Maestra of 

 Cuba. Here on the comparatively dry southern slopes 

 of the peak Torquino, at 3,500 feet, I found plants of 

 Cyathea arborea, a species which in- Jamaica and 

 elsewhere in the West Indies rarely ascends to more 

 than 2,500 feet. 



Similar conditions upon a grander scale are observed 

 upon the continent, the tree ferns being practically con- 

 fined to the humid Atlantic slopes and to the high 

 mountains. Thus in the mountainous parts of eastern 

 Guatamala (Alta Verapaz) where, according to the 

 native saying "It rains 13 months out of every 1£" tree 

 ferns are exceedinglv abundant, a few species occur- 

 ring at or near sea level but the most of them at from 

 4,000 to 0,000 feet altitude. West of this region, in 

 the dry interior basin, they are wanting; and only two 

 species, Cibotium Wendlandti and Hcmitclia costari- 

 censis are reported from the higher region near the 



84 



