CULTIVATION OF ORCHIDEOUS EPIPHYTES. 
265 
They are not seen farther north than Florida, where a single species, Epidendrum 
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 Orchidece exists in the same region as myriads of Tillandsia 
usneoides , which usually vegetates beneath the influence of the dampest tropical 
atmosphere. 
In the West India Islands they exist in vast quantities, particularly in Jamaica 
and Trinidad, not, however, so much upon the coast, as on 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. 
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 epiphytes are found ; but at Buenos Ayres, 
where the mean temperature is 67° 6', and the air dry, they are unknown ; and in the 
high dry land of Mendosa, where the aridity is still greater, the whole order almost 
disappears. 
On the west coast of South America, as high as Lower Peru, they are unknown ; 
a circumstance which will not be surprising, when we consider the effect of currents 
setting round Cape Horn, which bring the mean temperature of even Lower Peru 
itself down to 60° at night, and how arid the whole of that region is, with the 
exception of a few valleys. 
From this it may safely be deduced as a certain fact that the most favourable 
conditions for the growth of Orchideous epiphytes are a well drained soil, a shadv 
situation, a saturated atmosphere, the mean temperature of which is not less than 
from 79° to 80° ; and a complete protection from dry parching winds. Such appears 
to be the climate to which they are naturally subjected, in most cases; with the 
exception of the species found in the Mexican Andes. 
Two species are indeed found in Japan, the mean temperature of which is no 
doubt much lower than the heat stated above. 
If we reflect upon the natural habits of Orchideous epiphytes, and upon the 
little similiarity that often prevails between the atmosphere of hot -houses, and that 
in which, alone, it has been seen that they can exist, we shall cease to wonder at any 
failure that may have attended their cultivation. No accuracy was formerly observed 
in the proportion of vapour and temperature in the atmosphere of a stove ; a cir- 
cumstance which must have been fatal to many plants besides those now under 
consideration. Even at the present day, the air of many hot-houses would be found 
to indicate 6° or 7° of dryness, a condition to which such plants as these are never 
subjected by nature ; in those districts of the East and West Indies where such a 
climate prevails, we have seen that they disappear, but that as soon as atmospheric 
humidity increases sufficiently, they spring up in myriads from every tree. 
