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Plants\Trees
Rainforest Orchids
Photo: Courtesy of Damon Ramsey
BSc.(Zool) Biologist Guide
Rainforest Orchids:
The orchid family is a group of very hardy plants that are very
abundant in the wild. They belong to the family Orchidaceae, which is claimed by some authorities
to be the largest of the plant families.
There are some 230 species of orchids found in the Wet Tropics of
Queensland. This is between one-quarter and one-third of Australia's orchids. Their
evolution has enabled them to live in a variety of niches including growing on trees
(epiphytes), rocks (lithophytes) and in the ground (terrestrials). Some species have lost their chlorophyll and ability to derive energy from
sunlight. This means they must rely on are saprophyte fungi to provide food.
Orchids are characterised through their ways of animal
pollination and wind dispersal and their adaptations to these to give them their common
features. The pollen grains are massed into discrete parcels called pollinia to help with
efficient pollination as the parcels are easily carried around by insects. The orchid
flowers have evolved to entice the insect into doing this.
The flower is made up of three sepals which are similar to each
other and arranged radially, and three petals, one of which is modified to act as a
landing pad for insect pollinators. The female and male parts in the centre of the flower
are fused into a column with a single anther at the end. Some species have a lip designed
to mimic a female insect and attracts males to try to mate with it. The colours, shapes
and scents used to attract insects are numerous.
Ranked among the world's most attractive species is the Cooktown
Orchid. It has large pink coloured flowers - a common sight in the Cape York Peninsula
monsoon scrubs.
Orchids are abundant from Townsville to Cooktown in areas of
rainforest, open forest, mangroves, mountain tops and even eucalypt-dominated forests.
This diversity in habitats has resulted in the rich diversity in orchids.
Because of the widespread interest in orchids, they are collected
by many people, sometimes resulting in significant decreases in numbers of orchids. They
will need to be protected, which can be afforded to some extent by National Parks and the
World Heritage Area, but it must be recognised that simply declaring an area as a National
Park will not be fully protect the plants in it.
Growing native orchids is fine, but there are some rules that
should be followed: - 1. be aware of the legislation regarding collecting from the wild;
2. do not collect unless you have permission from the land owner; 3. only collect from
areas which have been or are to be cleared; 4. never buy orchids unless satisfied they
were obtained legally; 5. do not collect plants that you do not have the expertise or
conditions to successfully grow them; 6. do not collect more than you need for yourself.
In the Wet Tropics upland rainforests, large epiphyte orchids
occur on the larger trunks and forks, but the real diversity is often in the small
branches of the outer canopy. Terrestrial species such as the jewel orchid may be abundant
on the forest floor where there are rocks, on slopes where there is good drainage, or on
the banks of small streams.
A few of the many orchid species found in the Wet Tropics include
the Apricot Orchid, Pink Fingers, Jewel Orchid, Christmas Orchid, Leafless Nodding Orchid,
Northern Tangle Orchid, Tableland Pencil Orchid, Charging Bull Orchid, Fairy Bells and
King Orchid.
Additional Information:
Courtesy of
Damon Ramsey
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Many botanists believe it to be one of the most
highly evolved plant families, and there are indeed many species that have
elaborately specialised relationships with particular pollinating insects. They
are important to humans for various other reasons; for example, the flavour
vanilla comes from an orchid.
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It is also one of the
celebrated families, for the spectacular, elaborate flowers are prized by
flower fanciers all over the world.
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The flowers are often spectacular in the fact that they are
often colourful, or intricately patterned, and the uneven (zygomorphic) petal
arrangement often forms bizarre shapes. These are made from three sepals; two
lateral sepals that stick forward, and a high dorsal sepal, and three petals;
two lateral petals that stick out like wings, and the front hanging petal called
the labellum that hangs out like a tongue (Clarke and Lee 1997). The resulting
fruits are usually small, hard, dull capsules.
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The plants themselves are
usually only small, growing either as tiny ground herbs, or compact bunches
growing on trees or rocks.
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Orchids are found practically over
the world. However, they are much better known, and there are many more species,
in the tropics, where they grow mainly as epiphytes high in the rainforest
canopy.
Script: Courtesy of Damon Ramsey BSc.(Zool) Biologist Guide
Photo: Courtesy of C & D Frith
Australian Tropical Rainforest Life
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