FEBRUARY, 1923 } THE ORCHID REVIEW. 51 
GEOGRAPHICAL DISTRIBUTION OF ORCHIDS. 
EGARDING the geographical distribution of Orchids, Messrs. Veitch, 
in their Manual of Orchidaceous Plants, state that within what is often 
called the equatorial zone, a space extending to about twelve degrees on 
each side of the equator, and which includes nearly the whole of the 
Malaysian Archipelago and a great part of the continents of Africa and 
South America, the climatic conditions are such that epiphytal and other 
tropical Orchids are generally distributed, even in Africa, of whose tropical 
vegetation much yet remains to be investigated. It is within this zone that 
monopodial Orchids attain their greatest development; in Malaysia are 
found gigantic Stauropses and Grammatophyllums ; in Africa giant Angre- 
cums cling to massive Baobab and Iron-wood trees; and of sympodial 
Orchids gigantic Eulophias and Lissochili occur in certain places in the 
Congo and other regions of equatorial Africa in such quantities as to supply 
a feature in the landscape. Beyond this zone, both on the northern and 
southern sides, the distribution of Orchid life is much more irregular, being 
immensely influenced by local causes, especially by the direction of the 
trade and periodical winds by which the evaporation of the ocean is carried 
into certain localities more than in others, and also by the height and trend 
of the mountain ranges. 
A few well-known instances need only here be noted. In the eastern 
section—the mountains of Aracan and Moulmein, which receive the south- 
west monsoon on their western slopes—are the richest Dendrobe and Vanda 
districts known. The Khasia Hills and the lower Himalayan zone upon 
which, as already stated, is precipated much of the enormous evaporation 
raised in the Bay of Bengal is also an exceptionally rich Dendrobium 
region, and is besides the home of the finest Ccelogynes and Cymbidiums 
yet discovered. In the western section—on the Cordilleras of Venezuela 
and Colombia are aggregated most of the finest Odontoglossums, Cattleyas 
of the labiata type, Miltonias, Lycastes, Masdevallias, and numerous others 
highly valued by cultivators, caused by the constant action of the north-east 
trade wind in rendering the climate peculiarly suited to Orchid life. And 
from the action of the south-east trade wind, the coast range of Brazil with 
the country in its immediate vicinity is the home of many of the most 
beautiful Cattleyas, Lelias, Oncidiums, Zygopetalums, Sophronites and 
other Orchids prized for their large and brilliant flowers. 
On the mountain ranges of great altitude, as the Himalaya in the eastern 
and the Andes of Colombia and Peru in the western section, the vertical 
range of Orchids is considerable. On the Andes they ascend to elevations 
where the average annual temperature is less than in the lower and median 
latitudes of the temperate zone, some even ascending to the immediate 
