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Red Cross Spider Orchid
Caladenia cruciformis
A Threatened Species of the Heathy Woodland Community
Description
The Red Cross Spider Orchid is one of the large
group of ‘Spider Orchids’ in the genus Caladenia,
so called because of their long narrow petals and
sepals.
It has a single leaf, which can be up to 8cm long
and 8-10mm wide, sparsely hairy and sometimes
with a reddish tinge near the base. The flower
stem can be up to 25 cm tall, slender, hairy, and
usually dark green to purple in colour.
The flower (usually one but sometimes two) can
be up to 60mm across, with petals and sepals up
to 40mm long, rigidly spreading and forming a
distinctive cross-shape, which gives this orchid its
name. It is usually deep red to crimson, with
blackish club-like tips. The dorsal sepal is erect
and slightly incurved.
Spider Orchid Leaf
Red-Cross Spider Orchid
© Norm Stimson (Enviro Images)
© Norm Stimson (Enviro Images)
Distribution
The Red Cross Spider Orchid is restricted to a few
small areas in the central west of Victoria. The
largest known population occurs on private land,
but there are significant populations within
adjacent and nearby reserves.
Red-Cross Spider Orchids
Source: Flora Information System, DSE 2004
Photo: Adrian Morton
Red Cross Spider Orchid
(Caladenia cruciformis)
Habitat
The Red Cross Spider Orchid is found in heathy
woodland on grey sandy loam soils.
The
overstorey is usually Red Stringybark and Red
Box, sometimes with Grey Box, Yellow Gum or
Buloke. The shrub layer is typically a mixture of
Daphne Heath, Flame Heath and Common Fringemyrtle and associated herb species include Early
Nancy, Creamy Candles, Scented Sundew, Showy
Podolepis and a variety of other orchid species.
Decline and threats
It is likely that this species was once more
widespread, but the historical clearance of land
for agriculture, harvesting of timber for firewood,
and gravel extraction has removed or modified
much of its former habitat. Current threats to the
Red Cross Spider Orchid include unauthorised
firewood collection, grazing by native and
introduced animals, weed invasion, inappropriate
burning and illegal collection.
Life history
Similar Species
This species typically emerges as a small, single
leaf in late autumn. The leaf usually grows to
approximately 8cm long over winter, when the
bud forms.
Flowering usually begins in late
August, and may continue for several weeks
depending on seasonal conditions, and the
presence of pollinators.
Once pollinated, the
flower collapses and the ovary begins to swell.
Species similar to the Red Cross Spider Orchid
are Caladenia concolor (Crimson Spider Orchid)
and Caladenia formosa (Elegant Spider Orchid)
both of which are generally taller, have drooping
petals and sepals, and lack the blackish clubs of
the Red Cross Spider Orchid.
After several weeks the seed is ripe and the
capsule splits, releasing thousands of fine, black
seeds. From this time until the following autumn
the plant persists as a dormant underground
tuber, about the size of a marble.
Why are threatened species important?
•
Ecosystem maintenance – the complex nature of
ecosystem relationships means that the removal or
disturbance of one part of the ecosystem could
affect the functioning of many other components –
our knowledge of these relationships is incomplete,
so the results of loss or disturbance are
unpredictable
•
Plants provide us with all our food and a quarter of
our medicines – the potential of many plants to
supply food , medicines or other commodities
remains unexplored, and what other useful
compounds could exist in as yet undiscovered
plants?
•
Biological diversity is an intrinsic part of the
aesthetic qualities in
many areas valued in
Australia for tourism and recreation
•
Extinction is forever…
As with other Caladenia species, not every plant
will flower each year. In some years, it will
produce only a leaf, and in other years may
remain dormant as a tuber.
Conservation Status
The current known population of the Red Cross
Spider Orchid is approximately 1100 plants. It is
classified as ‘Endangered’ under the Victorian
Flora and Fauna Guarantee Act (FFG) 1988. This
species is included in the ‘Recovery Plan for
Twenty-five threatened Orchid Taxa of Victoria,
South Australia and New South Wales 2003-2007’.
Published by the Victorian Government Department of Sustainability and Environment
Melbourne, September 2005 © The State of Victoria Department of Sustainability and Environment 2005
This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968.
Authorised by the Victorian Government, 8 Nicholson Street, East Melbourne.
For more information contact the DSE North West Regional Office (Bendigo) on 5430 4444.
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