belt their elevations remove them from the hot and sultry climate conditions 
common to tropical lowlands. An instance of this may be seen in a comparison 
between two Mexican centres at which meteorological records have been kept; 
Merida at an elevation of 70 feet and Tulancingo at a height of 7,088 feet above 
sea-level. 
MERIDA TULANCINGO 
Month Temperature Rainfall Temperature Rainfall 
from to Ave. per Mth. from to Ave. per Mth. 
pais ee pi $7" 96 pts. 31° al 60 pts. 
Bene are 8° 92° 805; 32° 80° 44 ,, 
Mar. a5) 60° 97° $28) 34° 5° igh 
pl ee 64° 98° 88 ,, 38° 86° 140 ,, 
May 374 65° 98° 284°, 38° 96° 204 ,, 
Jane os.c4 74° 103° 664 ,, 42° 865° 384 ,, 
daly.’ -cigziet 72° 95° 432) >, 45° 82° B72 t, 
Be dss 7%, 94° S72 55 45° 82° 200): 55 
Sept. satu: 74° 95° 584 ,, 46° 80° AT2tG 
Wet. em 69° 93° 560043 40° AD; DED ~ 2 
NOW elses 62° 90° A725 36° 83), 60 5, 
Bree ee ia Se) 90° 124) 5, 33° 80° 44 ,, 
We see from this table that during their Winter period the rainfall is particularly 
low—for five months in succession the rainfall in the higher altitudes is less 
than one inch per month. It will also be noted that the maximum temperature 
never rises to 100° F., and that for seven months of the year it falls below 40’. 
These are the conditions under which Odontoglossums grow naturally, though in 
the case of the Colombian, Bolivian and Guatemalan species the Summer and 
Winter rainfalls are higher. It is obvious from this that a hot steamy atmosphere 
will not suit them. They must, therefore, be given a cool situation with constant 
moisture. I am, therefore, inclined to believe that a shady spot under a tree 
which protects them from the too direct rays of the sun, but which nevertheless 
allows them plenty of light, will suit them best. 
Under natural conditions they grow upon the trunks of tall trees or in the mossy 
forks of the branches where the thick moss so common to mountain trees grows. 
This moss remains damp at all times. In cultivation a mixture of osmunda and 
polypodium will give best results, about 50/50 of each being ideal. This compost 
will allow of the retention of reasonable moisture at all times, and will also allow 
the free circulation of air about the roots. 
Care must be taken in watering them for they are very liable to damp-off, particu- 
larly if water lodges in the young growth. The best way of watering them is to 
apply water to the compost by watering-can, and keep the surroundings wet at 
all times but avoid actually wetting the plant itself. Watering twice a day in 
Summer will be desirable, while about twice a week in the cooler period will 
suffice. 
It is better to under-pot rather than to over-pot this genus. The best procedure 
will be to repot annually, in the Autumn, with fresh compost, changing into a 
219 
