Pimelea spinescens subsp. pubiflora
The Wimmera Rice-flower Pimelea spinescens subsp. pubiflora is a small shrub 5-50cm tall which occurs on Buloke grasslands and was until recently presumed to be extinct. It had last been recorded from the Dimboola and Borung districts in 1901, however rediscovery of this species occurred in Spring 2005 when a population was discovered on a roadside in the Wimmera region of Victoria. Another population was also discovered near Natimuk in 2007.
The Wimmera Rice-flower is one of two subspecies of Spiny Rice-flower Pimelea spinescens, which are both restricted to Victoria. The other subspecies, Spiny Rice-flower Pimelea spinescens subsp. spinescens is classified as ‘Vulnerable’ under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (the ‘EPBC Act’) and is listed as ‘Threatened’ under the Flora and Fauna Guarantee Act 1988 (the ‘FFG Act’).
Since discovery of two populations the conservation status of the Wimmera Rice-flower has been changed from Presumed Extinct to Critically Endangered.
The flowers are critical in distinguishing the two subspecies. The Wimmera Rice-flower has flowers that are hairy on the outer surface whereas those of the Spiny Rice-flower are quite hairless. Flowering occurs in mid winter (April-August), in contrast to most other grassland species, with a profusion of small creamy yellow flowers. The spine-tipped nature of the stems distinguishes both the Wimmera and Spiny Rice-flower from all other Rice-flower species. Seed is produced from October to December.
The main threats are associated with physical soil disturbance through road maintenance and construction of fire breaks. Grazing is also recognized as a problem.
Recovery work on this species has begun with meetings held on site to discuss the short and long term management requirements for the population. These have included neighbouring landholders, and representatives from the Department of Sustainability and Environment (DSE), Royal Botanic Gardens Melbourne, Parks Victoria, local Shire, Country Fire Authority, and the Australian Native Plants Society. Other actions which have been implemented by DSE include searching for new populations, identifying potential habitat, liaison with stakeholders, propagation of plants, establishment of a seed bank collection and monitoring to increase understanding of the species. These will eventually form part of the Recovery Plan.
The site is also a good example of remnant grassland vegetation, and having survived the clearing and degradation that has occurred on many other roadsides, is a great example of how important it is to protect remaining native vegetation. The Wimmera Rice-flower is part of the Wimmera Threatened Flora Project, which is funded federally by Natural Heritage Trust via the Wimmera Catchment Authority. Pauline Rudolph from the DSE in Horsham is a key contact for this species (03) 53620754.
- Seed has been collected from both populations and provided to a local nursery to propagate plants for reintroduction in winter 2011.
- A draft reintroduction plan was developed and circulated within the Pimelea Recovery Team and appropriate stakeholders for comment.
- Germinants were again observed at both populations. An autumn ecological burn was conducted at the Minyip site to try and reduce wild oats. Wimmera Rice-flower was recorded re-sprouting following an ecological burn at the site in autumn 2009. A seed trial using a variety of treatments was conducted to investigate the effectiveness of the 2009 ecological burn in germinating seed. There was no positive germinants observed from this trial.
- Monitoring of the five 1 x 1 m quadrates at the Natimuk population didn’t detect any germinants and showed a small loss of plants from 2009 to 2010 (5 plants).
- Several roadsides were surveyed during winter of 2010 in an attempt to locate additional populations between Natimuk and Minyip, with no success. Meetings were held on site with Horsham Rural City Council to discuss weed management at the Lake Road site resulting from the 2008 road maintenance clearance. Weeds are still an issue in the road verge and table drain area that was impacted by the road maintenance works.
- The Royal Botanic Gardens has commenced a genetic diversity study, progress has been slow due to difficulties in obtaining appropriate genetic markers suitable to this subspecies. Results regarding the diversity of plants at both populations should be available in 2012.
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