Microtis angusii

Family: Orchidaceae

Conservation Status

Endangered species in NSW (TSC Act). Also listed as an endangered species at national level in the Endangered Species Protection Act.

Distribution

Microtis angusii, which was first discovered in 1987, and formally described and named in 1996 (Jones 1996), is known from just two widely disjunct sites, one at Ingleside and the other at Sunny Corner State Forest, 100 km west of Sydney (National Parks and Wildlife Service 1999b).

Pittwater Population

The Ingleside population is located within the Mona Vale Road road reserve at the junction of the Pittwater and Warringah Local Government Areas. In September 1998 a total of 336 plants were counted at this site (National Parks and Wildlife Service 1999b).

Habitat

The natural habitat of this orchid is unknown as both confirmed locations are highly disturbed. The Ingleside population occurs in a ridgetop site that has been cleared of its original vegetation, used as a soil depot and vehicle parking site, and the dominant species at the site are now introduced weeds (Acacia saligna and Hyparrhenia hirta).

It is possible that Microtis angusii may have been transported to the site as seeds within dumped soil (National Parks and Wildlife Service 1999b). The most likely natural habitat of Microtis angusii in the Pittwater-Warringah area is the Duffys Forest Vegetation Community, which has been listed as an endangered ecological community and is discussed below in section 2.6.1.

Ecology

Microtis angusii is a terrestrial orchid. For most of the year it is present only as underground tubers. It produces leaves and then flowering stemsusually in late winter and spring (National Parks and Wildlife Service 1999b).

Flowers have been recorded from May to October (Jones 1996). Other Microtis species flower prolifically after fires, and the same is probably true of M. angusii. Microtis flowers mature from the bottom of the inflorescence to the top, and the capsules at the bottom of the inflorescence may have released their seed before the flowers at the top have opened. By summer the above ground parts have withered and there is no visible evidence of the species.

Most Microtis species reproduce vegetatively by the formation of 'daughter' tubers from the main tuber, and can produce huge clonal colonies this way (Bates1986). It is likely that M. angusii reproduces vegetatively in the same manner. Other Microtis species have been reported to use a 'three chance' system forreproduction from seed. That is, they produce seeds through the use of insects as pollination vectors, self fertilisation (autogamy) or production of seedwithout pollination (apomixis). However, not all species are capable of autogamy or apomixis.

M. angusii produces large quantities of minute seeds (Jones 1996), but little is known about seed production, dispersal, germination and recruitment in thespecies. It may be that the species reproduces primarily by vegetative means and that seed production is relatively unimportant (National Parks and WildlifeService 1999b). It is unclear at this stage what factors trigger germination in Microtis angusii, or what level of seedling recruitment occurs. The time fromgermination to flowering is usually less than twelve months in Microtis species (National Parks and Wildlife Service 1999b).

Management Issues

• Recovery plan - a draft plan has been prepared (National Parks and Wildlife Service 1999b)
• Lack of knowledge of the biology and ecology of the species
• Fire management (fire is likely to be an important factor in the life cycle, but the most appropriate fire regime for the species is unknown)
• Habitat degradation (the only known site in Pittwater has been severely and repeatedly disturbed, and some level of disturbance, natural or otherwise, may be beneficial in promoting reproduction in the species, but other forms of disturbance are likely to be detrimental, such as soil compaction, rubbish dumping and overgrowth by weeds)
• Translocation (as an alternative to conservation in situ)
• Unauthorised collection of plant material (as a rare orchid, Microtis angusii is a possible target for unscrupulous orchid collectors)
• Community education

Updated: 06 Dec 2011