Orchid Hunting in the Wet Tropics Michael Harrison, NSW

ORCHID HUNTING IN THE WET TROPICS
Michael Harrison
One of my favourite things is to go out into the bush searching for native
orchids. To see these plants in the wild brings an added perspective to the
pursuit of growing them in cultivation. You are able to observe closely the
general and local forest conditions, the preferred host, the micro-environment
each species chooses, levels of light, aspect and air movement. When you put
these things together, along with the general climatic details, you can get some
real insights into how best to create suitable growing conditions for the plants
in your care.
However, whilst many orchids are relatively common, and many areas
support a wide range of species, it can be frustratingly difficult at times to find
them. Experience helps enormously, for like anything else, the more you do it
the better you get. Once you get a feel for it, you can usually locate orchids as
long as you are in the right kind of area. Often, you have a sense that a
particular spot just looks and feels right, so you go searching. At times, in
forest areas, you can be driving along and see a spot that you feel sure will
have orchids, due to the types of trees and vegetation, the density of the
foliage, and land form and aspect. Do not expect to see too much from the
car, or even as you walk along the road or track. Probably, you will see a few,
but nothing like the full complement. You need to step off the road and into
the forest, scanning as you go, up and down, and back and forth. It can take a
while to get your eye in, but once you start seeing orchids, more and more
seem to pop up. The further you walk into and through the forest, the more
you will see, so persistence is crucial, especially when you are searching for a
particular species.
Many orchids grow high up in rainforest trees, and whilst you may be able
to see a few of the larger plants from ground level, it will be impossible to
appreciate just how many there may be in the upper limbs and crowns. A
broken off branch or, if you are lucky, an entire fallen tree, will give you a
chance to see some of these high canopy species. It is important to take your
time and look carefully, for many of the miniature species are quite cryptic.
They may be surrounded by epiphytic ferns and mosses, closely adhering to
the bark, and all but invisible at first glance. But the thrill of finding
something unusual, or even a species you have not previously seen, is worth
the effort. It can be an exhilarating experience to come across an orchid you
cannot immediately recognise, for there is always the chance of finding a
previously unknown species.
The Wet Tropics of Queensland World Heritage Site was added to the
UNESCO World Heritage Listing in 1988. It consists of nearly 9000 square
kilometres of rainforest in north Queensland, stretching from Townsville to
Cooktown, for a distance of around 450 kilometres. Fifteen percent of the
area is protected in national parks, with the remainder being state forest,
reserves, crown or state land, and private freehold. Extending altitudinally
from sea level to above 1600 metres on the highest peak, Mt. Bartle Frère,
with significant areas above 1000 metres, this area provides an enormous
range of environments and habitats for a multitude of orchid species. Rainfall
varies considerably, with elevation, aspect and topography being major
influences. Annual rainfall varies from 1200mm to over 8000mm, with much
of it falling during the wet season, between November and April. The terrain
is mostly quite rugged and densely vegetated, with many steep hillsides and
fast flowing streams.
Whilst many areas may be intersected by forest roads, there are large
tracts that can be navigated only by foot. The going can be tough, with hard
climbs in often muddy conditions, but the rewards are worth it. Leeches and
ticks are a constant irritation, and snakes should be avoided, but to reach an
otherwise inaccessible spot high on a mountain, and to be surrounded by
gardens of wild orchids clinging to the trees and rocks, is one of the best
experiences in the world.
A field trip into any section of the Wet Tropics is always an exciting
adventure, and you are bound to see something unexpected. Down on the
coast, where conditions are distinctly tropical all year round, many orchids can
still be seen. Much of the lowland areas have been progressively cleared over
the years for agriculture, especially sugarcane. But in places like Daintree
National Park and Cedar Bay National Park, large areas of lowland
tropical rainforest survive, along with
paperbark forest and mangrove swamp
forest. Tropical orchid species which
are commonly encountered include
Dendrobium discolour, often a giant of
a plant with tall sprays of twisted, shiny
tan flowers, Den. smillieae, the
bottlebrush orchid with densely packed
heads of white, green and pink flowers,
and the ubiquitous Bulbophyllum
baileyi, its purple spotted flowers
giving off a lovely fruity fragrance. In
the paperbark forests, Dendrobium
canaliculatum is abundant. Dockrillia
calamiformis and Dockrillia rigida both
Dendrobium smillieae
grow in a range of situations, with a
preference
for strong light. They commonly colonise mangroves, as does the much rarer
Dendrobium nindii, with its sprays of flamboyant purple blooms. But if you
go looking in there, beware of the crocodiles, and remember, it’s the one you
don’t see that will get you.
In a few secret spots towards the top end of the Wet Tropics, the striking
pink flowers of the Cooktown Orchid, Dendrobium phalaenopsis, can still be
seen, but locations are guarded closely. This orchid grows in tangled vine
thickets, close to rainforest or along watercourses, usually in bright light.
In the low coastal
ranges, where the dense
tropical rainforests take
over, a marvellous array of
species can be seen.
Dendrobium
capitisyork
carries heads of tall spidery
flowers,
spotted
and
blotched in brick red. A
number of Eria species are
present, with E. kingii, E.
eriaeoides, E. fitzalanii,
and
E.
queenslandica
regularly encountered. In
Appendicula australiensis
some places Appendicula
australiensis, Rhipidorchis micrantha and Bulbophyllum radicans are locally
abundant. Huge clumps of Pholidota imbricata cling to high forest limbs, and
many a large staghorn fern provides a home for Cymbidium madidum.
Grastidium baileyi and G. cancroides produce semi-pendulous stems clothed
in grassy foliage. Their ephemeral flowers are produced from nodes along the
stems.
In the monopodials, a delightful miniature species, Schoenorchis
micrantha, carries multiple sprays of tiny, crowded, white flowers just 2mm
across. Robiquetia gracilistipes can grow to impressive proportions, with
pendulous spikes of yellow flowers with orange spots. A similar colour
scheme is found in the flowers of Pomatacalpa macphersonii. Phalaenopsis
rosenstomii is, of course, the queen of the jungle, its arching sprays of
crystalline white flowers a sight to behold in the subdued forest light.
Many of the lowland species extend to moderate elevations as well, but as
the altitude increases, the mix of species gradually changes. Such species as
Dendrobium jonesii and Cymbidium madidum are common. Three miniature
creeping species, Dendrobium lichenastrum, D. prenticei and D. toressae start
to appear but can be easily overlooked. Dendrobium monophyllum also
becomes apparent, growing on large boulders and cliff faces, as well as on
large tree branches. Its yellow flowers, carried on upright racemes, are
sweetly perfumed. The north Queensland form of D. gracilicaule (also known
as D. nitidus) can be seen from around 500 metres upwards. A tall elegant
plant, it produces sprays of yellowish green flowers, with pale reddish
blotches on the backs of the floral segments.
Bulbophyllum newportii, with white flowers and a yellow lip, and B.
macphersonii, become increasingly common. Cadetia taylori grows on trees
and rocks, often in large numbers. Its relatively small white flowers are quite
charming, and the labellum colour ranges from cream, through yellow to
orange/red. Dockrillia nugentii clings closely to the trunks and limbs of
rainforest trees, and will also grow on rocks. Both D. calamiformis and
Dockrillia rigida may be seen up to around 300 metres altitude.
But the largest and most diverse
concentration of species occurs in
the highlands, from 800 metres and
above. These cool, wet forests
support a wealth of orchid flora,
quite
dissimilar
in
their
requirements to the lowland
species. Moss and lichen encrusted
limbs may be almost completely
covered in orchids at times, with a
number of species growing
together.
Dendrobium
Dendrobium agrostophyllum
agrostophyllum becomes common,
its bright yellow flowersshining in
the sunlight.
It often grows
alongside Dendrobium jonesii,
which produces sprays of 50mm
tall, white flowers. Both species
prefer situations of bright light, and
large plants grow to sizeable
proportions. In a few spots, where
rocky outcrops are a feature of the
topography, they also establish
themselves as lithophytes.
Dendrobium fleckeri
The beautifully perfumed flowers of Dendrobium adae come in a range of
colours from white, through cream, green, yellow and apricot. It often occurs
in abundance. Once above 1000 metres, its less common relative, D. fleckeri,
starts to appear, producing chunky orange flowers with a spicy fragrance. D.
cacatua, with long, 4-sided pseudobulbs, carries heads of spidery, apple-green
flowers. It prefers to grow in well shaded spots, usually near watercourses. It
is closely related to D. capitisyork, seen at lower elevations.
Dendrobium carrii, a relative of D. monophyllum, colonises the outer
branches of tall rainforest and cloud forest trees, where it generally grows in
bright light. The flowers are white or cream, with a yellow or orange lip.
Dockrillia aff. calamiformis, a typical pencil orchid, is common, and
usually is seen perching high in a tree, swaying in the breeze. When in flower,
it covers itself in sprays of white flowers, sparkling in the dappled sunlight.
Dockrillia racemosa is less frequently seen. It has an upright habit of growth
and produces an erect inflorescence with yellowish green flowers.
The Bulbophyllums explode in diversity and numbers in these highland
forests. Bulbophyllum johnsonii, in its various floral and colour forms, is
common, with another related, creeping species, B. bowkettiae, also regularly
seen. The fleshy-leafed species in section Oxysepalum are variously
distributed throughout the highlands. All produce their relatively small
flowers from nodes along the stems, but in full bloom they can be spectacular.
B. schillerianum, with bright orange flowers, and B. wadsworthii, with
greenish yellow flowers, are the most common, followed by B. gadgarrense,
also usually a yellow to orange flowered species. Less commonly seen are B.
lewisense, with pure white flowers, B. windsorence, carrying green flowers,
and B. grandimesense, also with green flowers.
Bulbophyllum sladeanum
Dendrobium adae
Bulbophyllum macphersonii seems to be everywhere in some places, its
small, gem-like purple flowers fluttering in the breeze. B. sladeanum is
related, but far less common. It also produces purple flowers, but larger and
on a taller inflorescence. B. newportii and B. lilianiae are plentiful, the latter
usually colonising the small upper branches of rainforest trees. B. lageniforme
is a less common, clump forming species that generally grows closer to the
ground on tree trunks. It carries sprays of yellowish green flowers with pink
stripes on the segments. Other endemics include B. evasum, an unusual
species with a capitulate floral habit, B. nematapodum, with hooded, green
flowers, and the semi-pendulous B. radicans, with small, pink-striped flowers
borne under the leaves.
Several Sarcochilus species are present. S. borealis (or probably,
correctly, S. parviflorus) is a rainforest dweller, most often seen on trees
along streams. It is related to S. olivaceus, and carries pendulous sprays of
green flowers with a white, red-barred lip. Commonly seen growing in similar
circumstances is S. serrulatus. It produces sprays of shiny, nut-brown flowers,
and its specific epithet refers to the distinctly serrulate leaf margins. The
northern form of Sarcochilus falcatus, usually in flower in winter, grows high
up in rainforest trees, but also may be seen colonising trees in open, breezy
situations in paddocks and along road verges.
Other commonly seen monopodials include Plectorrhiza tridentata and P.
brevilabris, closely related but subtly different in floral form. Mobilabium
hamatum sometimes occurs in copious numbers, always in situations of bright
light and strong air movement. It has an upright, almost climbing vegetative
habit, and usually produces multitudes of racemes from nodes along the
woody stems. Infrequently seen are Rhinerrhiza divitiflora and Peristeranthus
hillii.
Within its genus, Liparis nugentiae is Australia’s largest flowered species,
with upright inflorescences carrying yellow blooms with an orange lip, up to
20mm tall. L. angustilabris produces delightful arching sprays of small,
yellowish brown flowers. L. bracteata grows on trees or on boulders on the
forest floor. It has green flowers about 10mm tall.
Miniature species such as Octarrhena pusilla and Plexaure crassiuscula
may occur prolifically, smothering a tree trunk or branch, with hundreds of
plants to the square metre.
It is a true wonderland of orchidaceous splendour, and to spend time in the
search for these wonderful plants is a privilege and an absolute pleasure.
68 Howes Road, East Kurrajong, NSW 2758
Email: mwharrison@ozemail.com.au
February 2014