Prostanthera spinosa (a shrub) - vulnerable species listing
The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the shrub Prostanthera spinosa F. Muell. as a VULNERABLE SPECIES in Schedule 2 of the Act. Listing of vulnerable species is provided for by Part 2 of the Act.
This species is now know as Prosthanthera sejuncta. This Determination should be read in conjunction with the 2016 Minor Amendments Determination.
NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. Prostanthera spinosa (family Lamiaceae) is described by Conn (1992) as a scrambling, + prostrate shrub, to 0.5 m high (erect and to 2 m high in Vic. & S.A.), aromatic; branches glabrous or hairy, at least at nodes, sparsely glandular, with regular decussate spines to 16 mm long. Leaves with lamina narrow-ovate, 1.5-6 mm long, 1-4 mm wide; apex obtuse; base acute to + obtuse; margins entire and slightly recurved; surfaces light to dark green, lower surface paler, glabrous or with a few stiff spreading hairs below, moderately covered with + sessile glands on lower surface; petiole 0.4-1 mm long. Flowers axillary; bracteoles persistent, 0.9-2.5 mm long. Calyx 3.5-6.5 mm long; tube 2-3 mm long; upper lobe 1.5-3 mm long, not enlarged in fruit. Corolla 8-14 mm long, pale mauve, very pale lilac to almost white. Anthers with appendage 0.7-2.1 mm long. Flowers July-Dec.
2. Prostanthera spinosa occurs in NSW, Victoria and South Australia. In NSW it is located within a small area to the north of Grafton in the NSW North Coast bioregion (Thackway & Creswell, 1995). It grows in skeletal sandy soils of rocky areas (Conn 1992). The NSW occurrence of P. spinosa is very restricted and disjunct, separated by more than 1000 km from other occurrences in Victoria and South Australia, and may represent a distinct taxon (B. J. Conn, pers. comm.).
3. There are five populations of Prostanthera spinosa known from confirmed records, and possibly several other small populations from anecdotal sightings in Banyabba Nature Reserve. The confirmed records include locations within Fortis Creek National Park and Banyabba Nature Reserve. All known populations are within a linear range of 16-20 km. Available information suggests that each population comprises tens to hundreds of individuals. Not all of these individuals may be mature.
4. The main threats to Prostanthera spinosa include frequent fire and environmental stochasticity due to the species' geographically restricted distribution and small local populations. Standing plants of P. spinosa are apparently killed by fire and, while the species may have a soil seed bank, its germination cues and seed longevity are unknown. Fire history data for the Banyabba - Fortis Creek area indicate that single fires may burn the entire NSW range of the species, and that most of the range of P. spinosa has been burnt in 2-4 extensive wildfires within a 15 year period from 1986/87 to 2002/03 (Department of Environment and Conservation, fire history records). "High frequency fire resulting in the disruption of life cycle processes in plants and animals and loss of vegetation structure and composition" is listed as a Key Threatening Process under the Threatened Species Conservation Act.
5. In view of the above the Scientific Committee is of the opinion that Prostanthera spinosa is likely to become endangered in New South Wales unless the circumstances and factors threatening its survival or evolutionary development cease to operate.
Dr Lesley Hughes
Chairperson
Scientific Committee
Gazettal Date: 18/11/05
Exhibition Period: 18/11/05 - 13/01/06
References
Conn B (1992) Lamiaceae. pp 623-64 in: G. Harden (ed.) 'Flora of New South Wales. Volume 3'. (New South Wales University Press: Kensington.).
Thackway R, Creswell ID (1995) (eds) 'An interim biogeographic regionalisation of Australia: a framework for establishing the national system of reserves.' (Australian Nature Conservation Agency: Canberra).