Red Darling Pea - profile

Indicative distribution

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Key:

known

predicted

The areas shown in pink and/purple are the sub-regions where the species or community is known or predicted to occur. They may not occur thoughout the sub-region but may be restricted to certain areas. ( click here to see geographic restrictions). The information presented in this map is only indicative and may contain errors and omissions.

Scientific name: Swainsona plagiotropis

Conservation status in NSW: Vulnerable

Commonwealth status: Vulnerable

Profile last updated: 02 Mar 2022

Description

Small prostrate forb to about 15 cm high, with densely white-downy stalks. Leaves composed of 13-25 narrow leaflets, each 10-15 mm long and 1-4 mm wide. Flowers reddish-purple or bright red, pea-like with a prominent upwardly-curved keel petal. Pod hairy, 15-25 mm long.

Distribution

Occurs in the upper Murray River valley in the south-western plains of NSW and into Victoria. Most NSW records are from the Jerilderie area, with possible collections from the Louth-Bourke area and a disjunct record in the north-western plains from Buttabone Stud Park 35 km NW of Warren. Also rare in Victoria, restricted to a few sites in the central north, mostly between Bendigo and the Murray River south of Echuca.

Habitat and ecology

Grows on flat grassland and in heavy red soil, often on roadsides and especially in table drains. Soils are derived from quaternary sediments and are usually red-brown clay-loams. The species is absent from black low-lying soils.
Recorded from roadsides, rail reserves, stock routes and areas of lightly grazed unimproved pasture comprising Austrodanthonia, Enteropogon acicularis and Austrostipa grassland communities.
Associated species include Austrostipa aristiglumis, A. nodosa, A. setacea, Homopholis proluta, Chloris truncata, Austrodanthonia caespitosa, A. duttoniana, Enteropogon acicularis, Hordeum spp., Lolium rigidum, Rhodanthe corymbiflora, Calotis scabiosifolia, Microseris lanceolata and Chrysocephalum apiculatum.
Swainsona plagiotropis appears to be an indicator species of Enteropogon and Austrostipa grasslands, communities which are poorly known and almost extinct. Other significant plants found in these grassland communities include Sclerolaena napiformis, Swainsona murrayana, S. sericea, Brachyscome chrysoglossa, Leptorhynchos panaetioides and Maireana excavata.
Flowering is from August to November, with fruit maturing in November. The species is a perennial, but the lifespan is unknown.
Plants die back over summer and remain dormant over several months as a subterranean woody root. When temperatures drop and sufficient rains have fallen towards autumn end, the roots begin to resprout. Growth is slow over the cold winter months, but by September plants have produced considerable foliage and buds begin to flower. Most flowers successfully develop into pods, containing an average of 20 seeds. By the beginning of November plants are rapidly maturing and the aerial foliage begins to die back.
Some form of disturbance (for example, light grazing at appropriate times, occasional soil disturbance or periodic fire) appears to be necessary to reduce competition and enhance seedling growth of Swainsona plagiotropis within grassy swards.
As with most other hard-seeded pea species, it is likely to require fire, prolonged wet conditions or soil disturbance to break the water-impermeable testa of the seed and allow germination. The large numbers present at Jerilderie 18 months after a fire and after two successive wet seasons support this hypothesis. Light grazing also reduces grass cover, maintaining an open sward and allowing sufficient inter-tussock space for germination and establishment.
Populations are variable in size, ranging from a handful of individuals to many thousands. The species is often prolific in good seasons and abundances vary from locally rare to abundant. Collections from the NSW north-western plains were from a population of 100+ plants scattered over 2 hectares.

Regional distribution and habitat

Click on a region below to view detailed distribution, habitat and vegetation information.

Threats

Habitat loss and degradation (further expansion of pasture improvement, crop cultivation and rice farming in grassland habitats).
Grazing by domestic stock can have an adverse impact on the species, particularly when grazing is during flowering and fruiting times.
Town expansion (and cultivation of the private land around Jerilderie).
Weed competition (mainly Lolium perenne, Arctotheca calendula, Phalaris aquatica, Trifolium and Hypochaeris species).
Trampling by stock (when the soil is wet).
Lack of biomass control (mainly natives and some weeds) through burning/grazing. This threat mainly applies to the reserve site.
Roadworks, gravel dumping and herbicide use (on roadsides and rail reserves).
Tree planting (groups involved in tree planting projects may not be aware of significant species in their sites).
There is no up to date distributional information, except at Jerilderie Nature Reserve. All the other site information dates from 1990-1991.

Recovery strategies

Priority actions are the specific, practical things that must be done to recover a threatened species, population or ecological community. The Office of Environment and Heritage has identified 9 priority actions to help recover the Red Darling Pea in New South Wales.

Activities to assist this species

Advise land holders and managing authorities on significant sites and practical conservation guidelines.
Protection of sites from grassfires.
No further degradation or loss of potential habitat.
Protection from insect attack.
Protection from grazing and associated physical disturbances.
Fence and signpost priority sites.
Weed monitoring and control in population areas.
Formalise the management of key sites via conservation agreements between land managers and the NSW NPWS and nominate areas warranting nature reserve status.
Monitoring and protection of populations from overgrazing.
Baselines surveys required to confirm known and locate new populations.

Information sources

Appleby, M.L., McDougall, K.L. and Barlow, T.J. (1991) Conservation research statement for Swainsona plagiotropis F. Muell. (Red Swainson-pea) NSW National Parks and Wildlife Service, Western Region: Broken Hill.
Benson, J.S., Ashby, E.M. and Porteners, M.F. (1996) The native grasslands of the southern Riverina, New South Wales. Report to the Australian Nature Conservation Agency. (Royal Botanic Gardens, Sydney)
Benson, J.S., Ashby, E.M. and Porteners, M.F. (1997) The native grasslands of the Riverine Plain, New South Wales. Cunninghamia 5(1): 1-48
Briggs, J.D. and Leigh, J.H. (1996) Rare or Threatened Australian Plants. Revised Edition. (CSIRO Publishing, Melbourne)
Chappell, A.C. and Luke, D.O. (1994) A community based action plan for the protection of Swainsona plagiotropis in the Jerilderie and Urana districts of New South Wales (Australian Nature Conservation Agency, Endangered Species Program, Project Number 305
Chappell, A.C. and Luke, D.O. (1995) 1995 Census of Swainsona plagiotropis populations in the Jerilderie district of NSW - an update on ANCA project 305 (1993 & 1994) (Landserv Pty Ltd: Bendigo).
Chappell, A.C. and Luke, D.O. (1996) 1996 Census of Swainsona plagiotropis populations in the Jerilderie district of NSW - an update on ANCA project 305 (1993 to 1995) (Landserv Pty Ltd: Bendigo).
Chappell, A.C. and Luke, D.O. (1997) Swainsona plagiotropis in the Jerilderie district of NSW. Data from permanent transects in September 1997 and continuation of ANCA project 305 (1993 to 1996) (Landserv Pty Ltd: Bendigo).
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992) Plants of Western New South Wales. (Inkata Press, Sydney)
Foreman, P. (1994) A recovery plan (research phase) for Swainsona plagiotropis in the Jerilderie and Urana districts of NSW (NSW National Parks and Wildlife Service: Hurstville).
Lee, A.T. (1948) The genus Swainsona. Contributions from the New South Wales National Herbarium 1(1): 132-271.
Leigh, J.H. and Briggs, J.D. (eds.) (1992) Threatened Australian Plants - overview and case studies. (Australian National Parks and Wildlife Service, Canberra)
Mueller, F.J.H. von (1875) Swainsona plagiotropis F. Muell. Fragmenta Phytographiae Australiae 9: 153.
Thompson, J. (1993) A revision of the genus Swainsona (Fabaceae). Telopea 5(3): 427-581.
Thompson, J. and James, T.A. (1991) Swainsona. In Harden, G.J. (ed.) Flora of New South Wales. Volume 2 (New South Wales University Press: Sydney).
Walsh, N.G. and Entwisle, T.J. (1998) Flora of Victoria; Volume 3, Dicotyledons Winteraceae to Myrtaceae. (Inkata Press, Melbourne)
Webster, R. (1998) Results of 1998 Swainsona plagiotropis counts (Ecosurveys Pty Ltd: Deniliquin).