#ThreatenedSpecies of the Week: Caladenia wanosa, Kalbarri Spider-orchid

Caladenia wanosa, which is more commonly known as the Kalbarri Spider-orchid.
Caladenia wanosa, more commonly known as the Kalbarri Spider-orchid, is listed as Vulnerable under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 and as Declared Rare Flora under the Wildlife Conservation Act 1950.

The Kalbarri Spider-orchid is endemic to Western Australia. Currently there are 16 known populations – 11 occur near Kalbarri, three are south of Mullewa, one is near Eradu, and the other is within East Yuna Nature Reserve. Eight of these populations occur in national parks and nature reserves, with the rest occurring on pastoral leases, unallocated crown land and road verges. The populations combined contain an estimated 300 mature plants. The species is considered to be fragmented as the known populations are scattered with considerable distances between them.

Caladenia wanosa occurs as scattered individuals. The plant is up to 20cm tall, with an erect linear leaf 3–6cm long and about 3mm wide, with hairs mainly on the lower surface. Flowers are cream with deep maroon markings and the erect upper sepal and spreading lateral sepals all have prominent clubs. The attractive labellum (flower lip) is broad, with bold red stripes and a curved tip. It has two rows of dark red calli. Flowering occurs from August to September (so it’s the perfect time to get out there and see if you can spot this one!)

Near Kalbarri, Kalbarri Spider-orchid grows in sandy soil under tall shrubs of Murchison Clawflower (Calothamnus homophyllus) and Kurara (Acacia tetragonophylla), among sandstone outcrops, often on the upper edges of gorges. Near Mullewa, the species inhabits deep, yellow loamy sand beneath tall shrubs of Jam (Acacia acuminata) and hakea species with emergent Mallee.

The main identified threats to Kalbarri Spider-orchid are invasive weeds, grazing by feral goats, rabbits and sheep and substrate disturbance by feral pigs. Almost all populations outside the conservation estate are recorded as having high levels of weeds in adjacent vegetation. Grazing is noted as being a problem in the majority of populations. Feral pigs appear to be causing habitat degradation in all conservation estate populations. The main potential threats to Kalbarri Spider-orchid include firebreak maintenance, roadworks, car park extensions, drought and wildfire. It is said to be ‘desirable’ to protect this species from fire where possible, during the plant’s vegetative and flowering phase (August to September).

Information Source: Government of Australia; Department of Environment & Energy, and the Department of Biodiversity, Conservation and Attractions.

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