Indicative distribution
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.
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click here to see geographic restrictions).
The information presented in this map is only indicative and may contain errors and omissions.
Scientific name: Pimelea venosa
Profile last updated:
11 Oct 2023
Description
This upright shrub has stems and leaves densely covered with whitish, soft, spreading hairs. The dull green leaves are narrowly oval-shaped or slightly wider at the end, 10 - 15 mm long and 4 - 6 mm wide, and are softly hairy. Veins on the leaves are prominent and brown. The small white flowers are usually bisexual and are covered in coarse hairs. Flowers grow in heads of two to six. Fruit is approximately 3 mm long and green. The species is distinguished by the densely hairy leaves and stems, and the prominent brown primary and secondary veins on the leaves. Unless heavily grazed, leaf clusters are often terminal on long bare stems, which become recumbent gradually. Plants are typically 1 m in height. On more fertile soils, plants can mature into dense bushes that are 2 x 2 x 2 m.
Distribution
This rice-flower species occurred primarily in the Bolivia Hill and Bluff Rock Ranges south of Tenterfield. Observations over the past decade suggest that this highly palatable species might have been widespread prior to the introduction of domestic stock. Surveys at previously occupied sites and in potential habitat conducted in 1999 found no plants. Sites that were burned by wildfire were re-surveyed in 2012 in hopes of post-fire sprouting but no plants were seen. One new population of the species was discovered in 2012, the first seen in over 15 years. It too gradually declined and all plants died by 2017. However, a subsequent low intensity wildfire in the area during late 2019, followed by consistent rainfall, stimulated sprouting of 800 seedlings including in nearby areas that were not occupied by mature plants in 2012. Three smaller populations ranging from 4 - 250 individuals have subsequently been found within a kilometre of this regenerated population. In 2021 a second large population of approximately 1000 plants was found in the region, occupying more fertile black loams.
Habitat and ecology
- Flowers were originally reported to appear from October to December. However, both well-studied populations flower prolifically during late winter in many years, yet peak in November during others. Plants as young as four months are capable of flowering abundantly, although most mature only after one year. Variability in growth rate can be extreme, with similar-aged plants in close proximity being an order of magnitude different in biomass, potentially due to root constraints and competition in subsurface granite.
- Associated vegetation is dominated by Eucalyptus species, with an open understorey of Xanthorrhoea and Solanum species. The limited records provide no clear search pattern for further populations using community associations.
- Previously recorded as occasional and localised, e.g. in populations comprising less than 50 plants. No wild recruitment has been observed until recently. Volunteer seedlings in nursery conditions and garden trials have been stimulated to germinate by solely the provision of consistent water, possibly triggered by appropriate cool temperature regimes. The abundant seedling response 8 months after a low-intensity fire followed by consistent rain suggests interacting factors may cause pulses in population appearance and survival. However, seedlings occur sparsely within the second population which has not been burnt in many years.
- National Parks purchased Bolivia Hill in 2000 and the area is now managed as a Nature Reserve. Extensive searches of the area have found no extant wild populations. Translocations are proposed, comprising both establishment of ex situ created plants and sowing of abundant seeds.
- Bolivia Hill Rice-flower has been recorded on deep granite soils, black sandy loam and relatively fertile loam soils on granite outcrops in open woodland. Partial shade may benefit the species, although garden plants have been recorded growing and reproducing strongly in both full shade and full sun. While mature plants have previously been found most commonly growing at the base of boulders, recent observations suggest that correlation is due to more exposed seedlings being accidentally crushed by herbivores or more readily browsed.
Regional distribution and habitat
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Threats
- Clearing of habitat for grazing, roadworks and railway track maintenance.
- Grazing by domestic stock, macropods and other herbivores.
- Browsing by feral goats, and associated soil compaction, erosion and nutrient addition.
- Risk of extinction from stochastic environmental events due to the highly restricted distribution, typically small population sizes and repeated failure of observed populations to recruit juveniles.
- Plants have been observed being eaten by caterpillars, and some larger stems are hollowed out by borers enough to break off.
- Inappropriate fire regimes including fire frequency, intensity, seasonality, and scale.
- Insufficient understanding of species ecology, especially the triggers necessary to stimulate recruitment that maintains consistent populations.
- Insufficient understanding of threats.
- Competition and habitat degradation caused by feral goats and deer.
- Browsing from native herbivores damaging individuals.
- Highly restricted distribution and small population size increasing risk of extinction from stochastic environmental events.
- Insufficient understanding of germination requirements.
- Insufficient understanding of species distribution.
Recovery strategies
A targeted strategy for managing this species has been developed under the Saving Our Species program; click
here for details. For more information on the Saving Our Species program click
here
Activities to assist this species
- Control of feral goats.
- Protect areas of potential habitat during roadworks or railway track maintenance. Protect plants from grazing so that they can re-create a soil seed bank.
- Protect areas of deep granite soils or black sandy soils on granite in the Bolivia Hill region from clearing.
- Notify the DPE of any new occurrences of the species.
- Potential habitat should be searched opportunistically for new records of this species, especially following bushfires and consistent rainfall.
- Determine response to fire and manage local populations to protect mature plants and achieve recruitment.
- Propagate multiple genetic strains to provide diversity for translocation sites.
- Develop techniques to cost-effectively ensure consistent yearly germination among wild populations.
- Reintroduce genetically diverse populations to secure sites where protection and reliable monitoring are feasible, including on private properties where citizen scientists are interested in contributing to conservation of the species.
Information sources
- Briggs, J.D. and Leigh, J.H. (1996) Rare or Threatened Australian Plants. Revised Edition. (CSIRO Publishing, Melbourne)
- Harden, G.J. (1990) Thymelaeaceae. Pp 375-388. In: Harden, G.J. (ed.). Flora of New South Wales. Vol. 1. UNSW Press, Kensington, NSW.
- Hogbin, P. (2002) Review of the Threatened Species Conservation Act Flora Schedules: Recommendations to the Scientific Committee.
- Hunter, J.T. and Earl, J. (1999) Field Survey to Determine the Locations and Distribution of the Threatened Plant Pimelea venosa Threlfall. Report to the Northern Directorate, New South Wales, National Parks and Wildlife
Service.
- Jacobs, S.W.L. and Pickard, J. (1981) Plants of New South Wales. A census of the cycads, conifers and angiosperms (Royal Botanic Gardens: Sydney).
- NSW Herbarium Records. () Databased specimen records from the National Herbarium of New South Wales (Royal Botanic Gardens: Sydney).
- NSW National Parks and Wildlife Service (1999) Threatened Species Information: Pimelea venosa (NSW National Parks and Wildlife Service: Hurstville).
- Rye, B.L. (1990) Thymelaeaceae. 9. Pimelea. 37. Pimelea venosa Threlfall. In George, A.S. (Ed) Flora of Australia 18: 172.
- Threlfall, S. (1982) The genus Pimelea (Thymelaeaceae) in eastern mainland Australia. Brunonia 5(2): 113-201.
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