48 Upon the Cultivation of Epiphytes of the Orchis Tribe, 



the Colony is probably at least equal to that of the Mauritius, yet 

 the aridity of the region prevents a trace of them being seen. 



In America, their favourite station, according to Humboldt, is in 

 the gorges of the Andes of Mexico, New Grenada, Quito and Peru, 

 where the air is mild and humid, and the mean temperature 63° — 67° 

 Fahr. (17° — 19° cent.) In these localities they are so abundant, that 

 according to the authors of the Flora Peruviana above 1000 species 

 might be found in Tarma, Huanuco and Xauxa alone. They are 

 not seen further north than Florida, where a single species, Epiden- 

 drum conopseum, is found on the Magnolia ; but it is well known 

 that the vicinity of the gulf of Mexico, and the effects of the gulf 

 stream, give the vegetation of Florida, a tropical, rather than extra- 

 tropical appearance. In that country this solitary representation 

 of tropical Orchideae exists in the same region as myriads of Til- 

 landsia usneoides, which usually vegetates beneath the influence of 

 the dampest tropical atmosphere. 



In the West India Islands, they exist in vast quantities, particu- 

 larly in Jamaica and Trinidad, not however so much on the coast 

 as upon the lower ranges of hills. This is in conformity with their 

 habits elsewhere ; in these islands the air of the level of the sea is 

 very dry, while that of the mountains is unusually humid. Captain 

 Sabine found the air of the level of the sea at Trinidad indicate 

 5° of dryness, and that of Jamaica, 7°; while the atmosphere was 

 saturated with humidity in the first of these Islands, at 1060 feet 

 above the level of the sea, and in the second at an elevation of 4080 

 feet. 



At Rio Janeiro, the mean temperature is 74° 3', and much higher 

 inland ; there the woods are so damp that it is difficult to dry plants, 

 and in such situations inconceivable multitudes of Orchideous Epi- 

 phytes are found ; but at Buenos Ayres where the mean tempera- 

 ture is 67° 6' and the air dry, they are unknown ; and in the high 

 dry land of Mendoza where the aridity is still greater, the whole 



