#ThreatenedSpecies of the Week: Caladenia elegans

Caladenia elegans, or the Elegant Spider Orchid, is listed as Endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC) and as Declared Rare Flora under the Wildlife Conservation Act 1950.

The elegant spider orchid is endemic to Western Australia and is found west-north-west and east of Northampton. It is known from just eight populations, growing amongst open Melaleuca low scrub in low heath in winter-wet depressions.

Caladenia elegans is an erect tuberous herb to 30 cm high. It has up to three large creamy-yellow flowers, 5 to 8 cm across and dark maroon hairs on the tips of the slender, filamentous petals and sepals. The pale yellow labellum (lip) is striped with dark red. The edge of the labellum has irregular teeth and the calli (glands) are in two rows. Flowering occurs from late July to August.

As for other terrestrial orchids, seed germination of Caladenia elegans relies on the presence of a species specific mycorrhizal fungus. This symbiotic relationship is essential for any seedling establishment. Although very large quantities of seed are released from each capsule, few grow to maturity. Caladenia elegans does not require fire to complete its life cycle, however there is some evidence to suggest that it may benefit from fire every ten years or so. Fire opens up the understorey, thereby reducing competition for space and light, and provides a source of nutrients for the growth of mycorrhiza on which Caladenia elegans seedlings depend for their establishment and growth. Adult plants are probably long-lived (tens of years), and flower regularly every year. Flowering is synchronised within and among populations to produce an expansive bloom of short duration. The flowers are sweetly scented and pollinated by male thynnid wasps, possibly attracted in response to pheromones emitted by the flowers.

The main threats include weeds, habitat loss, water erosion, accidental destruction associated with road and track maintenance, grazing and destruction by feral animals (feral pigs and rabbits), inappropriate fire regimes and chemical drift.

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

Related Posts

Leave a reply