‘Nothing
is more extraordinary in the history of
the
vegetable kingdom, as it seems to me, than the apparently very sudden
and abrupt development of the higher plants.’
--
Charles Darwin
in a letter to botanist Sir Joseph Hooker of Kew Gardens, 1881
Darwin was
fascinated by orchids. In his Origin
of Species
he mentioned the ‘inexhaustible number of
contrivances’ by
which orchids ensure their pollination, pointing out that these would
have entailed changes in every part of the flower.
Know
the Origin
Orchids are not that difficult to grow if you know where they come
from. The trick is to replicate their native environment in your home.
Some orchids bloom in the winter because they are native to the
southern hemisphere; others are fragrant only in the evening in order
to attract the nocturnal birds and insects they needed for pollination.
Insect Mimics
Orchids come in many shapes and sizes, the best known probably being
the insect–mimicking species. Many of these mimics have very
ingenious ways of attracting pollinating insects, appealing to the
senses of both sight and smell.
One of the most amazing of these mimics is the Bucket Orchid, which
comes in two species, Coryanthes
speciosa and Stanhopea
grandiflora. Bucket orchids
are pollinated by the males of two
species of bee — Euglossa
meriana and Euglossa cordata
— which themselves are specially designed for the task.
Attracted by the smell of nectar emanating from the orchid,
the
bee gathers from the surface of the flower a liquid which will make him
attractive to female bees.
The surface of the orchid is slimy, which causes the bee to slip and
fall into the ‘bucket’ that contains a pool of
liquid
dripping from a gland above. The only way the bee can escape is through
a tunnel, and there is a convenient step leading from the pool of
liquid to the tunnel entrance.
As the bee is about to escape from the tunnel, the walls of the tunnel
contract, gripping the bee. The plant’s mechanism then glues
two
pollen sacs to the bee’s back. After allowing time for the
glue
to dry, the bee is released. If the bee then flies to another bucket
orchid, the same process will take place, except that this time, when
the bee attempts to leave the tunnel, a hook in the roof of the tunnel
removes the pollen sacs, and the fertilization process is completed.
Care
and Maintenance
The three key components to growing orchids are humidity, water and
soil conditions. Different varieties of orchids have different
preferences about climate, nutrients and water. Again, it is important
to know the native environment of the particular species being grown.
Most orchids thrive in about 60% humidity. Indoors, they may need help
in the form of a nearby saucer filled with rocks and water, or a humidity
tray.
Orchids grown indoors often require a special orchid fertilizer, and a
special potting medium to help them grow.
How
To Repot Orchids
When you repot an orchid plant, your intention should be to provide new
and fresh media rather than just a larger pot. Most orchids do not grow
well in too large a pot, as they will concentrate on root
development and stop growing upwards. Repot
your orchid in 5 easy steps.
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