Plants of
South Australia
Caladenia venusta
Orchidaceae
White Spider-orchid,
Large White Spider-orchid
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Regional Species Conservation Assessments per IBRA subregion.
Least concern
Near threatened
Rare
Vulnerable
Endangered
Critically endangered
Extinct
Data deficient
Adelaide
Arkaroola
Ceduna
Coober Pedy
Hawker
Innamincka
Marla
Marree
Mount Gambier
Oodnadatta
Renmark
Wudinna
Keith
Yunta
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Botanical art

Kath Alcock paintings: 10

Prior names

Arachnorchis venusta

Calonema floribundum

Caladenia floribunda

Caladenia patersonii, partly

Common names

White Spider-orchid

Large White Spider-orchid

Etymology

Caladenia from the Greek 'callos' meaning beauty and 'aden' meaning a gland; referring to the colourful labellum and the glistening glands at the base of the column that adorn many of the species. Venusta from the Greek 'venusta' meaning attractive, graceful, alluding to the appearance of the plant.

Distribution and status

Found in the lower South-east in South Australia, growing in damp heathland, open forest and woodland. Also found in Victoria. Native. Very rare in South Australia. Rare in Victoria.
Herbarium region: South Eastern
AVH map: SA distribution map (external link)

Plant description

Annual terrestrial orchid growing from an underground tuber, to 60 cm tall with one or two large flowers and a single basal leaf. Flowers are white to pale pink with a toothed labellum, which has a red margin and red calli. Tepals are 12 cm long. Flowering between September and November. Fruits are brown papery ellipsoid capsule. Seeds are very small brown ellipsoid seed with a long translucent brown mesh-like covering.

Seed collection and propagation

Collect seeds between January and February. Collect fat capsules as they start to dry and turn brown. Pods will split and release the seeds quickly and will require monitoring. To increase the chances of collecting mature pods, it is recommended that a small breathable bag (ie. Organza bags) be used to enclose the developing capsules. Place the capsules in a container that will hold fine seeds and leave to dry for a few weeks or until the capsule split. Then carefully hold the capsule and tap it gently to release the seeds. Store the seeds with a desiccant such as dried silica beads or dry rice, in an air tight container in a cool and dry place, refrigerator or in liquid nitrogen. For the NVC South East Orchid Project three populations consisting of more than 70 individuals in total were recorded from Willalooka, Nangwarry and Bolara Native Forest Reserve. Approximately 1,020,000 seeds (0.65 g) were banked from these three populations. The seed viability for the collection made from Willalooka area was very low at 8%. The other collections were higher at 49% and 65%. Seed germination in Caladenia species is difficult without compatible mycorrhizal fungi.

Seeds stored:
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LocationNo. of seeds
(weight grams)
Number
of plants
Date
collected
Collection number
Collection location
Date
stored
% ViabilityStorage
temperature
BGA540,000 (0.374 g)12 pods25-Nov-2013T. Horn
South Eastern
1-Nov-201649%-80°C
BGA380,000 (0.266 g)14 pods19-Nov-2013DJD2774
South Eastern
1-Nov-201665%-80°C
Location: BGA — the seeds are stored at the Adelaide Botanic Gardens, MSB — the seeds are stored at the Millennium Seed Bank, Kew, England.
Number of plants: This is the number of plants from which the seeds were collected.
Collection location: The Herbarium of South Australia's region name.
% Viability: Percentage of filled healthy seeds determined by a cut test or x-ray.