Diuris disposita (a terrestrial orchid) - endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list Diuris disposita D.L. Jones., a terrestrial orchid, as an ENDANGERED SPECIES on Part 1 of Schedule 1 of the Threatened Species Conservation Act. Listing is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. The donkey orchid Diuris disposita (Family Orchidaceae) was first described in 1993 by Jones, from the Kempsey area on the north coast of NSW.

2. Diuris disposita is a terrestrial herb. Leaves 1 or 2, linear, 15-30 cm long, 4-5 mm wide, conduplicate. Raceme 20-35 cm high, 2-7 flowered, widely spaced. Flowers yellow with brown markings on the dorsal sepal and labellum, c. 2 cm across. Dorsal sepal ovate, 7-11 mm long, 4-7 mm wide, obliquely erect, margins recurved. Lateral sepals linear to oblanceolate, 10-24 mm long, 1.5-2 mm wide, deflexed, parallel or crossed. Petals obliquely erect; lamina broad-elliptic to obovate, 6-9 mm long, 4-5-6.5 mm wide; claw 4-7 mm long. Labellum 7-9 mm long; lateral lobes linear to oblong, 2-2.8 mm long, 0.8-1.2 mm wide; midlobe narrow-ovate to ovate when flattened, 4-7 mm wide, ridged along midline; callus of 2 divergent, incurved ridges c. 4.5 mm long. Flowers Sept.-Oct. Grows in moist grassland in sclerophyll forest (Harden , 1993. Flora of NSW, Vol. 4. p.143).

3. The species is known only from eucalypt forest with grassy understorey in the Kempsey area, on the north coast of NSW. It is currently known from 3 populations, 2 within State Forests and a further population on freehold land.

4. A total of less than 50 plants is known and none occur in a reserve.

5. The species is threatened by habitat destruction, inappropriate fire regimes and collecting of plants. The risk of extinction is high due to low population numbers.

6. In view of 3, 4 & 5 above the Scientific Committee is of the opinion that the species is likely to become extinct in nature in NSW unless the circumstances and factors threatening its survival cease to operate. Hence, Diuris dispositais eligible to be listed as Endangered on Schedule 1, Part 1 of the Threatened Species Conservation Act.

Proposed gazettal date: 6/11/98
Exhibition period: 6/11/98 - 11/12/98