Tetratheca juncea

The Black-eyed Susan (Tetratheca juncea) is so named because of the deep purple coloured centre of the flower of this otherwise difficult to observe small shrub. This species is frequently observed within suitable habitat areas comprising of woodlands, heaths and dry sclerophyll forests, predominantly within the Lake Macquarie area. T. juncea re-sprouts strongly after bushfire but populations can be severely adversely affected if frequent fires occur within its growth areas. Although somewhat difficult to detect when not in flower, large populations can be observed in some areas when it is in flower.

Conservation status

Listed as vulnerable in NSW under Schedule 2 of the Threatened Species Conservation Act, 1995. 
Also listed as vulnerable under the Commonwealth Environmental Protection and Biodiversity Conservation Act, 1999.

Description

Tetratheca juncea is a spindly shrub with thin angular multi branching, weakly supported spreading stems 30 to 60cm long which develop from woody rootstock. Occasional leaves are narrow and short, up to 3mm in length. Flowers are downward facing, approximately 1cm in diameter with four light pink to purple petals, with a deep purple centre.^1&2

Other Characteristic Features

Growth Characteristics: This species can be decumbent (trailing) or erect and grows from 20cm to 1m tall.² Often grows amongst other shrubs where it then appears to be a small bush.

Flowers: Downward facing pink, fading to very pale pink, four petalled flowers with a purple centre. Flowers appear along the stems singly or in pairs from July to January.^1&2 Sometimes white flowers may occur.

Reproduction:  Reproduce by seed or clonally by underground stems, which can be up to 50 cm long. Pollinated by insects including native bees.²

Life Span: This species is a perennial and is often clonal and therefore the life span is difficult to determine. Individual clumps of T. juncea have been known to survive in excess of 7 years.³

Site Characteristics

Vegetation Type: Usually in low open forest/woodland, sometimes heathland and moist forest, with a mixed shrub understorey and grassy groundcover.^1&2

Topography: Slopes and ridgetops (occasionally lower slopes or drainage lines) with a variety of aspects, but most often on south-easterly aspects.^1&2

Soils: Most often located within low nutrient soil landscapes, predominantly those such as the Awaba and Warners Bay soil landscape units.^1&2

Where this Species can be Found

Map of distribution (PDF file, 1.2Mb)

Gosford:  Toomeys Road and Mount Elliot.

Wyong: Dooralong, Charmhaven, Lake Munmorah, Toukley, Catherine Hill Bay, Doyalson, Wyee, Warnervale.

Lake Macquarie: Cooranbong, Swansea, Wallsend, Wyee Bay. Belmont, Nords Wharf, Seahampton, Warners Bay, Kotara, Dudley, Avondale, Belmont, Wakefield, Cardiff.

Where is this Species Habitat Protected?

Gosford:  None.

Wyong: Munmorah State Recreation Area.

Lake Macquarie: Awabakal Nature Reserve, Wallarah National Park, Lake Macquarie State Conservation Area, Glenrock State Recreation Area, Lake Macquarie Recreation Area.

Threats to Survival

• Habitat loss due to clearing for land development.
• Habitat degradation resulting from frequent fire, weed invasion and stormwater runoff.
• Disturbance by recreational use, such as dirt bike riding and bushwalking.
• Fragmentation of populations through clearing and human disturbances.

This Species has been identified as being affected by the following Key Threatening Processes:

• Clearing of native vegetation.
• Invasion of native plant communities by exotic perennial grasses.
• High frequency fire resulting in disruption of life-cycle processes.

Management Issues

• Instigate appropriate fire regimes which protect the species from frequent fire.
• Install stormwater control mechanisms to prevent off-site impacts from development upslope of populations.
• Undertake weed control as required using removal methods that will not impact on the species, such as hand pull or cut and paint methods.
• Protect and actively manage large populations and those at the limit of the species range.
• Improve vegetative connectivity within and between populations through revegetation and regeneration programs.
• Monitor population health and numbers for any changes.
• Undertake targeted searches for the species in known or potential habitat during its flowering period prior to any clearing or development.

Useful Web Links:

• Department of Environment and Climate Change - www.dec.nsw.gov.au
• Plant Net – www.rbg.gov.au

Further Reading:

• BHP (1994) Field Observations into Tetratheca juncea Fire regeneration and Distribution within Lake Macquarie City Council. 
• Bellairs, S.M., Bartier, F.V., Gravina, A.J. and Baker K. (2006) Seed Biology Implications for the maintenance and establishment of Tetratheca juncea (Tremandraceae) a Vulnerable Australian species. Australian Journal of Botany Vol 54, Issue 1, 35-41.
• C.L. Murphy Ed. (1993) Soil Landscapes of the Gosford/Lake Macquarie 1:100,000 sheet, Soil Conservation Service of NSW.

Bibliography:

1. Bartier F.V., Gross C.L., Mulligan D.R., Bellairs S.M., and Bowen D. (2001) Understanding the biology and Ecology of Vulnerable Plant Species – A Case Study with Tetratheca juncea Occurring over Coal Leases, ACARP Project C8102. A report prepared for Australian Coal Research. June 2001.
2. Payne, R. J. (2000) Lake Macquarie Tetratheca juncea conservation management plan. Final report. November 2000. Unpublished report to Lake Macquarie City Council, NPWS and BHP Pty Ltd.
3. Payne, R.J., Stevenson D.A. & Wellington R. (2002) A standardised method for counting Black-Eyed Susan populations. Unpublished technical note.