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 Orchids
have always held a fascination for people, there is an air of mystery
surrounding them. Mention the word "orchid" and terms such as exotic,
rare, expensive, beautiful, colourful and unique will arise. Everyone
will have a different perception and all of these, no matter how diverse,
will be correct.
Over 30,000 different
orchid spicies are found on our planet, and well over 100,000 hybrid
strains have been artificially propagated. Many of these hybrids are
important commercial plants that are used as cutflowers and pot plantd
to satisfy strong demand, both lacally and internationally.
What makes orchids different
from other flowering plants? Their floral structure is obviously different.
Orchids have three petals and three sapals which may,or may not, be
alike. However, the third petals, known as hte lip or labellum, is
almost highly modified and quite different from the other sements
in size, shape and often colour. This structure often plays an important
part in orchid pollination. Another feature, which helps to define
orchids, is an appendage, known as a column, often located in the
centre of hte flower. The fleshy column combines the msle ( anther
) and female ( stigma ) sexual parts on one structure. The anther
and stigma are situated close together.
Orchid flowers use their
form, colour and often fragrance to attract many creatures which act
as pollinators. Bees, wasps, butterflies, months, flies, beetles,
ants and even birds assist the fertilization of orchid flowers. Numerous
orchid flowers actually mimic insects. Some deceive bees by looking
like other flowers that offer a reward, while other species, often
with deep maroon flowers, smell like rotten flesh, to attract flies!
Two main growth structures
are found in orchid ; monopodial and sympodial. Sympodial orchid,
such as Bulbophyllum and Dendrobium, have a main stem, or pseudobulb,
which is produced annually and matures at the end of each growing
season, often culminating with flowering. During the next season,
a new pseudobulb grows from the base of last season's growth. These
pseudobulbs, which hold water and nutrients, are produced along a
structure known as a rhizorne. Monopodial orchids such as Aerides,
Phalaenopsis and Vanda have main stems which grow constantly. These
main sterns produce flower spikes, correctly termed inflorescences,
from or opposite the leaf axil.
Orchid seeds are minute
and dust-like -- a single fruit or capsule has the potential to produce
up to a million seeds, depending on the species. However, orchid seeds
have little food storage and rely on a specific type of fungus for
their germination and development. The mortality rate in the wild
is enormous. Now, orchid seed are germinated in laboratories using
a synthetic agar solution. This technique has made it possible to
produce large quantities of both species and hybrids in a sterile
environment. Depending on the genus, orchid can take from twelve months
to twelve from germination to flowering. On average, most orchid flower
around four years from germination after starting our in life as green
blobs known as protocorms.
One fact that quickly
becomes apparent is that few orchid have"common" names. Many are simply
referred to by their generic name. Many other groups of plants are
known by their bolanical names, as common names, often with out the
users knowing it. Such tougue - twisting exampales include Agapanthus,
Bougainvilla, Chrysanthemum, Jacaranda and Rhododendron. These names
are derived from both Latin and Green, however, Latin has been used
extensively for scientific terms. This enables a universal system
for communication. A problem with common names is that one name may
refer to many completely different plants. Also, what may be a "local"
name in one a area may not be pertinent in another.
Over 75 percent of the
world's known orchid species occur in the tropics. This is a fact
that doesn't surprise many. What may surprise, however, is that the
majority of these "tropical" species (over 80 percent) inhabit the
cooler mountainous forests, at altitudes of over 1000 meters above
sea level. These montage forests provide homes for an amazing number
of diverse and unique plant and animal species that are found nowhere
else in the world.
In the tropics, most
orchids are epiphytes, that is, they grow on trees for support and
light. They are not parasitic, as terrestrials. Species that grow
in the ground are referred to as terrestrials. Most of the tropical
terrestrial orchid species are evergreen, unlike the deciduous terrestrials,
which are generally found in more temperate climates. After flowering,
these plants die down to storage organs, known as tuberoids, which
have a similar life - cycle to bulbs.
A small percentage of
orchids are saprophytes; these live off dead or decaying matter. There
are even two Australian orchid species which grow and flower completely
underground!
Only a small percentage
of the world's orchid flora is cultivated in specialist nurseries,
botanical institutions and private collections. Whilst the collection
of popular species from the rainforests can threaten the survival
of wild orchid populations, their main energy is habitat destruction.
Southeast Asia is one of the world's most densely populated regions,
and its virgin forest continues to be cleared and burnt. New species
continue to be discovered, and a number of "lost" species have been
relocated. Yet one wonders how many species, both plant and animals,
have become extinct before they have been recorded.
Fortunately, most of the
horticultural attractive orchid species are entrenched in cultivation
and have been propagated by division or by seed. The species at real risk
are the countless miniatures, or " botanicals" as they are known. These
have little commercial value and are of most interest to botanists and
orchid special enthusiasts
About the Author
David P.Banks has been growing orchid for over 25 years. He is a Past
Presidant of The Orchid Species Society of New South Wales, and of
the Panramatta and District Orchid Society, and has also served two
terms as Vice President of the Orchid Socirty of New South Wales.
He is a qualified orchid judge with the OSNSW as well as the Australian
Orchid Council and is the current Editor of The Orchadian and the
Australian Orchid Review. David's acclaimed photographs appear in
many journals and he lectures extensively throughout Australia and
overseas at workshops, society meetings and orchid conferences.
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