Diuris bracteata (an orchid) - endangered species listing

NSW Scientific Committee - final determination



The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list an orchid, Diuris bracteata Fitzg. as an ENDANGERED SPECIES in Part 1 of Schedule 1 of the Act, and as a consequence, to omit reference to Diuris bracteata Fitzg. from Part 4 of Schedule 1 (Species presumed extinct) of the Act. Listing of endangered species is provided for by Part 2 of the Act.

The Scientific Committee has found that:

1. Diuris bracteata Fitzg. (family Orchidaceae) is described by Jones, D. L. (1993) in Harden, G. (ed). Flora of New South Wales. UNSW Press. Vol. 4. p. 14 as: Leaves 2, linear, c. 10 cm long, c. 10 mm wide, conduplicate. Raceme c. 18 cm high, with c. 5 prominent, curved, linear bracts, c. 3-flowered. Flowers yellow with blackish markings, c. 1.6 cm across. Dorsal sepal ovate, c. 8 mm long. 6 mm wide, with blackish markings towards the base. Lateral sepals linear, c. 9 mm long, c. 1.5 mm wide, deflexed, crossed. Petals obliquely erect, divergent; lamina elliptic; claw blackish. Labellum c. 10 mm long; lateral lobes linear to oblong, c. 4 mm long, c. 1.8 mm wide, margins irregular; midlobe ovate to rhombic when flattened, c. 6 mm wide, ridged along midline; callus of 2 ridges c. 5 mm long. Flowers recorded Sept.

2. Diuris bracteata was known only from the original collection near Gladesville, made before 1889. In view of the absence of recent records Diuris bracteata was listed as Species presumed extinct on Part 4 of Schedule 1 of the Threatened Species Conservation Act.

3. Since 1998 specimens from the Sydney Basin Bioregion have been confirmed as Diuris bracteata.

4. Diuris bracteata is now known from a few sites in dry sclerophyll woodland, and the total number of individuals is about 50. The known populations do not occur in conservation reserves.

5. Several occurrences are on roadsides and are at risk from earthworks, herbicide spraying, slashing/mowing and illegal collection.

6. The small population sizes and limited area of extent means that survival is threatened by environmental and demographic stochasticity.

7. In view of the above the Scientific Committee is of the opinion that Diuris bracteata Fitzg. is likely to become extinct in nature in New South Wales unless the circumstances and factors threatening its survival or evolutionary development cease to operate.

Dr Lesley Hughes
Chairperson
Scientific Committee

Proposed Gazettal date: 21/10/05
Exhibition period 21/10/05 - 16/12/05


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Page last updated: 28 February 2011