Rare and threatened plants and fungi of Victoria

Orchid conservation at Royal Botanic Gardens Melbourne

Australia is home to more than 1,300 native orchid species. Most are terrestrial and found predominantly in Australia's south-east and south-west. There are also some epiphytes or lithophytes, growing on other plants or in crevices of rocky outcrops. Epiphytic orchids grow mostly in the forests along the eastern coast.

Victoria is a 'hotspot' for orchid diversity, with 23 per cent of Australia's orchid species in just 3 per cent of the land area. Most of the native orchid species found in Victoria are terrestrial, and at least a third occur nowhere else.

Many Australian native orchids are threatened (endangered, vulnerable or rare) and of increasing concern to conservation organisations. Without intervention, the great diversity of Australian terrestrial species may be lost.

Royal Botanic Gardens Melbourne's ex situ (away from the natural habitat) conservation research contributes to a collaborative project that aims to stabilise or increase populations of threatened Victorian orchids in situ (in the natural habiat). The research also involves the Victorian Department of Sustainibility and Environment, The University of Melbourne, RMIT University, the Australian Native Orchid Society, Melbourne Zoo and Parks Victoria. The orchid propagation and cultivation methods are researched and developed at RBG Melbourne.

The complex associations between the orchids and their associated microscopic terrestrial fungi (mycorrhizae) require specialised propagation techniques where orchid seeds are germinated in the presence of appropriate fungi isolated from orchids of the same species. This is known as symbiotic germination. The resultant orchid plants, with their fungi, are available for reintroduction into their natural habitats.

Nematolepis wilsonii back from the brink

A member of the Boronia family, the shrub Nematolepsis wilsonii (Shining Nematolepis) is known only from the edge of cool-temperate rainforest in the O'Shannessy River Catchment between Warburton and Marysville.

Prior to the Black Saturday fires of February 2009, about 200 adult plants were known and these were at threat of being damaged or destroyed by introduced Sambar deer. Sambar deer 'de-velvet' their new antlers each year and have decided that Shining Nematolepis has just the right surface for this task, but in doing so, they have been progressively ringbarking the shrubs, resulting in death of about 10 per cent of the population.

Fences have been erected to protect remaining plants. In addition, establishment of new populations in similar situations in an adjacent catchment was seen to be a good insurance policy for such a rare plant.

Staff from RBG Melbourne established over 300 plants from cuttings and seed in the Gardens nursery. These plants await translocation to a safe site in the Upper Yarra Catchment.

The O'Shannessy population of Shining Nematolepis was completely destroyed in the Black Saturday fires, but we hope that sufficient seed remained in the soil to re-establish the population. If not, new plants will be grown from stock plants retained at RBG Melbourne and from seed stored in the Victorian Conservation Seedbank.

Resurrection of Borya mirabilis

Borya mirabilis (Grampians Pincushion Lily) is the sole Victorian member of a group of plants principally native to Western Australia. It occurs on a small sandstone ledge in the Grampians National Park. Only five small colonies are known over an area of about 30 × 20 m, and in all would cover less than one square metre.

Plants from each of the colonies have been studied in detail for genetic differences and it appears that there is only a tiny degree (if any) of genetic separation between individuals. The plants appear to be self-incompatible (that is, flowers from one plant cannot fertilise themselves) and because the levels of genetic similarity are so high within the population, it functions as a single plant and no viable seed has been known to be produced since the rediscovery of the colony in 1980.

Staff at RBG Melbourne have been developing successful techniques for propagating plants vegetatively and have produced sufficient numbers to allow for the establishment of a second 'population' in a secure site some 20 km from the original population.

The natural population was severely burnt in the 2005 Grampians (Mt Lubra) fires, and it was not until some months later that plants began to resprout (no-one had documented their fire response previously). Even so, more than 50 per cent of the original population was lost in the fire. The newly established population did not burn.

Hypocreopsis amplectens – a rare and threatened fungus

The fungus Hypocreopsis amplectens is confirmed from only three sites in southern Victoria (Nyora, Grantville and Greens Bush) and from one location in New Zealand. All sites in Victoria are not far from the coast. It is found growing on another fungus (a species of Hymenochaete) which forms patches on dead branches of Tea Tree (Leptospermum). The thickets of Tea Tree are old and senescing, with many fallen dead branches. Fire is frequent in this vegetation, but the fungus seems to prefer long unburnt sites. In New Zealand, H. amplectens occurs in Nothofagus forest.

Collaboration between scientists at RBG Melbourne and in New Zealand and Austria led to the formal description of the species in 2007. Hypocreopsis amplectens differs from other species in the genus by the combination of verrucose ascospores which have one to three (and as many as seven) septae. DNA sequences from the ITS region are identical between New Zealand and Victorian collections.

Because of its rarity, specific host and habitat requirements, and the threats from inappropriate fire regimes, Hypocreopsis amplectens was the first fungus formally listed under the Victorian Flora and Fauna Guarantee Act, the legislation that protects rare and endangered species. It is interesting that in Europe Hypocreopsis lichenoides and H. rhododendri are also rare species.