i8o 
THK ORCHID 
The natural home of the Odontoglossum 
knows no winter or summer such as we are 
accustomed to. All the year through the 
plants enjoy a fairly regular temperature and 
condition of moisture. Now and again an 
excess of rain or a few weeks drought may 
appear unfavourable, but the plants arc so 
roliust that they quickly recover when more 
favourable conditions return. 
It must always be remembered that 
extremes of heat are as injurious as low 
temperatures. During the hot summer 
months all our care and attention will be 
required to keep the Odontoglossum house 
from getting too warm. The method of 
opening wide all the doors and ventilators, 
and thus allowing the hot and dry air to come 
in contact with the plants, is very injurious. 
The aim of the cultivator should be to keep 
the internal air as moist and cool as possible 
by careful shading and frequent damping 
down of all the staging and paths. With 
some of the old forms of greenhouses, in 
which the side ventilators are placed on a 
level with the staging, there is nothing to 
moisten the fresh air before it reaches the 
plants, but in the modern constructions ample 
ventilation is afforded almost on a level with 
the ground, and if some coarse sacking 
material kept constantly moist is suspended 
near the openings a very beneficial atmo- 
sphere will be maintained. Top ventilators 
will always be required, although they are 
often opened too widely, and thereby produce 
a draught. These only require opening 
just sufficiently to allow the heated air to 
escape. 
On all fine clays the foliage may be finely 
syringed with rain-water of the same tem- 
perature as the house, taking care that the 
greater part is evaporated before the close of 
day, especially if the coming night is likely to 
be cold. Careful cultivators will give a look 
at all the plants before leaving the house in 
order to find any plants with surplus water 
left standing in the new growth. Any plants 
in this condition should be turned over and 
the water shaken out. Slight moisture on the 
leaves is beneficial, but a new growth left full 
of water on a cold night will frequently be 
WORLD. [May, 1913. 
destroyed, although the damage may not be 
apparent until a few days have passed. 
Insect peS'S are not numerous, the principal 
one being thrip, which does an immense 
amount of damage in a comparatively short 
time. The new flower spikes are generally 
attacked, a sure indication being the rusty 
brown appearance and the arrest of develop- 
ment. These small insects are almost 
invisible to the naked eye, but the use of a 
lens will easily find them out. A dry 
atmosphere favours their increase, and in a 
short time they will completely spoil the 
whole plant. Early attention is necessary to 
prevent this pest spreading to every plant in 
the house, and, fortunately, its destruction is 
easily carried out by the use of a suitable 
insecticide, or washing the plants with a weak 
solution of soap and water. There are some 
growers who regularly spray their plants 
every second or third week with one or other 
of the various nicotine washes, and such prac- 
tice invariably maintains the house and plants 
111 a clean condition. Fumigation is very bene- 
ficial, especially when the house is in good 
structural condition and can be made to hold 
the vapour, but in old houses this is a difficult 
matter and the most satisfactory results will 
come from spraying and washing the plants. 
With Odontoglossums the amateur has a 
very wide and varied assortment to choose 
from, possibly larger than any other genus. 
Two species that may be regarded as the 
foundation of all the Odontoglossum hybrids 
are crispum and Pescatorei, the former gives 
size and substance, the latter branching 
spikes. The varieties of crispum are so 
numerous and beautiful that a house is often 
entirely devoted to their culture. With 
amateurs, however, this is not always possible, 
and in view of the elegant lu'brids now being 
produced it is not surprising to find a general 
desire to include as varied a selection as is 
possible with due respect to expenditure and 
accommodation. Odontoglossum Harryanum 
has worked wonders in the genus, not only 
with its strong constitution, but with its rich 
coloration. By its use we have hybrids too 
numerous to mention, yet almost all w^orthy 
of cultivation. 
