#ThreatenedSpecies of the Week – Caladenia bryceana subsp. cracens (Northern Dwarf Spider-orchid)

6Caladenia bryceana subsp. cracens is listed as Vulnerable under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and as Declared Rare Flora under the Wildlife Conservation Act 1950.

The main identified threats to Northern Dwarf Spider-orchid are grazing (feral rabbits (Oryctolagus cuniculus) and feral goats (Capra hircus)), hydrological change and weeds.

Caladenia bryceana subsp. cracens, also known as Northern Dwarf Spider-orchid, is a tuberous, perennial herb, from 3–8 cm in height, which produces a single, hairy leaf that is broad and may be as long as the flowering stem. The green flower, 14 mm wide, has a red tip on the labellum and dark red calli. The labellum is hinged at the base and the basal calli are fused to form a large clubbed projection with two lobes. Flowering occurs from August to early September.

Caladenia bryceana subsp. cracens differs from the subspecies Caladenia bryceana subsp. bryceana in its populations that are further north, paler flowers, curled petals and sepals and less globular calli, which are often absent from the centre labellum.

Northern Dwarf Spider-orchid is endemic to Western Australia and is known from 15 populations between Northampton and Kalbarri. The majority of populations occur on pastoral leases, with others occurring on private land, national parks and reserves. The number of mature plants which constitute these populations is estimated to be 400.

Northern Dwarf Spider-orchid grows scattered in low heath in shallow soil on coastal limestone. Further north it forms colonies on winter-wet flats or in swales beneath thickets of Melaleuca uncinata, over open herbs in pale red-brown sandy loam or brown sandy clay.

Information Source: Government of Australia, Department of Environment and Department of Parks and Wildlife Western Australia

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