Boronia serrulata (a shrub) - rejection of vulnerable species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to reject a proposal to list the shrub Boronia serrulata Smith (Native Rose) as a Vulnerable species on Schedule 2 of the Threatened Species Conservation Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Boronia serrulata (Rutaceae) is described by Harden (1991) [Flora of New South Wales, Vol 2]: a shrub 0.5-1.5m high; branchlets glabrous or rarely sparsely hairy with simple hairs, with 2 grooves separated by decurrent leaf bases. Leaves crowded, flattened over the stem, strongly aromatic, 1-foliolate; lamina broad-obovate, 7-18 mm long, 5-9 mm wide, apex acute, margins finely toothed, glabrous, thick, often red-tinged; more or less sessile. Inflorescences terminal, 1-4 flowered; pedicels 1-3 mm long or flowers more or less sessile. Calyx glabrous. Petals 7-11 mm long, imbricate, bright pink, glabrous, not persistent in fruit. Stamen filaments with swollen apex hairy. Style vestigial, concealed by the swollen stigma, glabrous. Cocci glabrous. Flowers Aug.-Oct. Grows in moist heath in sandy situations, chiefly in a coastal band in the Sydney district.

2. The species has a distribution restricted to Hawkesbury Sandstone in the Sydney Basin Bioregion, generally in heaths and woodlands and often associated with exposed sandstone rock outcrops. It is considered to be nationally Rare by Briggs & Leigh (1996) [Rare or Threatened Australian Plants, CSIRO, Australia]. The species is killed by fire and regenerates after fire from seed stored in the soil.

3. Protection of much of the distribution of Boronia serrulata occurs within the National Parks reserve system. It is found in a number of conservation reserves in the north (Brisbane Water NP, Marramarra NP, Muogamarra Nature Reserve, Ku-ring-gai Chase NP, Berowra Valley Regional Park, Garigal NP), south (Royal NP, Heathcote NP) and southwest (Dharawal State Conservation Area) of its range. Whilst the total population size is not known, a number of populations containing hundreds of plants are known and very large populations of thousands of plants are known from Ku-ring-gai Chase NP and Royal NP. However, population sizes of standing plants and soil seed banks are likely to vary with time since fire.

4. Within the reserves in 3) above the main potential threat to the species is too frequent fire. The species has survived two fires 5 years apart in Royal NP, but any continued repeated fire frequency of less than 5 years would be likely to cause declines.

5. In the past, it is thought that the species has declined in some areas as a result of picking for the wildflower industry, while other populations have been lost, and may continue to be lost, to clearing for urbanisation. Protection of populations outside the NPWS reserve system may assist the conservation of the genetic diversity within the species.

6. In view of 3, 4 & 5 above the Scientific Committee is of the opinion that the species is currently well conserved in the reserve system around Sydney and given appropriate fire management it is not likely to become endangered in nature in NSW.

Proposed Gazettal date: 27/8/99
Exhibition period: 27/8/99 - 1/10/99