Rhizanthella slateri (an underground orchid) - vulnerable species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the underground orchid Rhizanthella slateri (Rupp) M. A. Clem. and P. J. Cribb as a VULNERABLE SPECIES in Schedule 2 of the Act. Listing of vulnerable species is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Rhizanthella slateri (Rupp) M. A. Clem. and P. J. Cribb (family Orchidaceae) is described in Harden (1993, Flora of New South Wales, Vol 4, page 219, UNSW Press, Kensington) as a 'Terrestrial saprophytic herb with fleshy underground stem to 15 cm long and 15 mm diam., whitish, often branching, with prominent, fleshy, overlapping bracts. Flowering heads maturing below the soil surface or extending 2 cm above the ground, to c. 2 cm diam., the receptacle of up to 18 whitish triangular bracts to 8 mm long; flowers up to 30, tubular, purplish. Dorsel sepal curved, the tip narrowing linear to filiform, the base broad and hooding the column and most of the 2 lateral petals; lateral sepals erect, broad at base but each lateral sepal folding lengthwise into a filiform tip longer than the dorsal sepal and often protruding beyond the length of bracts making the cup. Lateral petals about half the length of the lateral sepals. Labellum claw a short, flexible hinge; labellum lamina cordate, thick, tongue-like with the upper surface covered with fine papillae. Column short and broad with column wings reduced to narrow, papillose 'ears'; anther broad and curving, stigma a thickened pad. Flowers Oct-Nov.'

2. Rhizanthella slateri ranges from southeastern Queensland to the south coast of NSW. In NSW, it is currently only known from fewer than 10 locations, including near Bulahdelah, the Watagan Mountains, the Blue Mountains, Wiseman's Ferry area, Agnes Banks and near Nowra. At each location, only a few individuals are known. However,  Rhizanthella slateri is difficult to detect, it is usually located when the soil is disturbed, and there may well be more locations of the species within its known range. The species grows in eucalypt forest but no informative assessment of the likely preferred habitat for the species is available.

3. Habitat disturbance has threatened the survival of the species at some of the known sites. One known site is subject to potential clearing for road construction. The small population size at known locations may make the species threatened by stochastic events.

(Rupp) M. A. Clem. and P. J. Cribb is likely to become endangered unless the circumstances and factors threatening its survival or evolutionary development cease to operate.

Proposed Gazettal date: 06/12/02
Exhibition period: 06/12/02 - 24/01/03