Variable Midge Orchid - profile

Indicative distribution

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Key:

known

predicted

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. ( click here to see geographic restrictions). The information presented in this map is only indicative and may contain errors and omissions.

Scientific name: Genoplesium insigne

Conservation status in NSW: Critically Endangered

Commonwealth status: Critically Endangered

Gazetted date: 17 May 2015

Profile last updated: 02 Nov 2023

Description

A terrestrial orchid with a solitary cylindrical leaf that encloses the flowering stem. The leaf is 6 to 15 cm long, 0.15 cm wide, and dark green with a reddish base. The flowering stem is 9 to 18 cm tall, bearing 5 to 12 flowers in a moderately dense spike, 15-25 mm long. Flowers are dark purple and approximately 5 mm in diameter. The species was reclassified to Corunastylis insignis in Orchadian 13(10): 461 (2002). The species is currently listed by the Commonwealth as Corunastylis insignis.

Distribution

Occurs in southern Lake Macquarie and northern Central Coast LGAs. It's distribution is recorded as far as Cooranbong in the north, Warnervale in the south and Chain Valley in the east.

Habitat and ecology

Appears to be associated with PCT 1636 Scribbly Gum – Red Bloodwood – Angophora inopina (not always present) heathy woodland on lowlands of the Central Coast and variations containing Angophora costata (Smooth-barked Apple).
Recent and historic disturbance regimes (fire, clearing, routine slashing) appear to influence above ground emergence (i.e. leaf and flowers). Several known sites exhibit a removed/managed shrub layer and canopy, therefore shading and competition/biomass is likely to inhibit above ground emergence. However, a lack of disturbance is not considered an adequate justification to exclude the potential existance of the species, as the species can remain dormant underground for a number of years and has been known to emerge and swarm in dense and intact vegetation after fire.
Known locations/populations of plants exhibit dormancy for greater than four years (likely to persist underground for greater than four years). Therefore, absence in a given year may be a 'false absence' and the plants can re-emerge once conditions are favourable (e.g. rainfall in winter and appropriate disturbance).
Grows in patches of Themeda triandra (Kangaroo Grass), which can be ephemeral. Other associated species include, but are not limited to, Mirbelia speciosa, Ptilothrix deusta, Leptospermum trinervium and Leptospermum juniperinum in wet (seasonal) heath settings, Banksia spinulosa and Xanthorrhoea latifolia, and Xanthorrhoea media.
Other seasonal and cryptic species commonly associated with known populations include: Cryptostylis subulata, Cryptostylis erecta, Thelymitra ixiodes, Thelymitra pauciflora, Microtis spp., Burchadia umbellata, Tricoryne elatior, Thysanotus juncifolius.
Population numbers of flowering plants fluctuates between years due to dormancy. The number of individuals in the meta-population is therefore an estimate and likely to be around 50 plants - monitoring of the populations through the Saving our Species program is informing population size.
Flowering period is typically from September to October, but has been recorded flowering as early as August and as late as November to early December. Note, this species is extremely difficult to locate even when in flower and cannot be definitively identified from leaf alone. Local climatic conditions appears to trigger flowering events, with flowers documented to appear 6 weeks following appropriate rainfall events. In drier periods, initial signs of above ground activity may emerge (e.g. leaf and spike), though flowers have been observed to wither in the absence of suitable conditions (e.g. soil moisture).

Regional distribution and habitat

Click on a region below to view detailed distribution, habitat and vegetation information.

Sydney Basin

Threats

Loss and fragmentation of individual plants/habitat as a result of activities such as infrastructure maintenance, clearing for development and inappropriate disturbance regimes.
Road and track maintenance activities.
Physical damage to plants and/or habitat as a result of recreational activities. Recreational activities may include be but are not limited to 4WDs, trail bikes, horse riders, orchid enthusiasts, bushwalkers, rubbish dumping, illegal collection of plants etc.
A restricted distribution and small total population size place the species at risk from demographic and environmental uncertainties, and natural catastrophes.
Competition and overshading from native and introduced plants
Invasive grasses overcrowding the species and reducing available habitat.
Browsing by feral herbivores such as rabbits on stems and damage/remove individuals above ground.
Insufficient understanding of the species ecology, including genetics, pollination, seed germination, mycorrhizae, reproductive ecology and response to fire.
Fungal attack from various strains of fungus - most likely naturally occurring strains. The fungus affects plant growth and seed production.
Browsing by native herbivores on leaf/stem can cause damage/remove the plants above ground parts.
Erosion of soils from nearby road verges impacting soil chemistry and substrate condition
Inappropriate slashing regimes during leaf emergence, flowering and fruiting periods impacting the species reproduction
Inappropriate fire regimes, including too frequent or infrequent fire impacting the species survival and reproduction
Risk of extinction from stochastic events due to small population size and restricted distribution. This plant also has a low reproductive rate.
Potential for thick undisturbed habitat that may prevent plants emerging and flowering.
Competition and overshading from native and introduced plants

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

Support and provide information to land managers and road/track maintenance crews regarding appropriate management.
Install gates, fencing and signs to manage access to sites.
Protect known habitat areas from clearing and disturbance.
Undertake monitoring of the known populations.
Prepare and implement site specific plans of management.
Map known sites and conduct surveys of potential habitat to locate new sites.

Information sources

Gunninah Environmental Consultants (2002) Wyong Ground Orchid Survey. Unpublished report prepared for Wyong Council.
Jones, D.L. (2001) Six new species and a new combination in Genoplesium (Orchidaceae) from Eastern Australia. The Orchadian Vol. 13 (7), 293-307.
NSW Scientific Committee (2001) Genoplesium insignis (a terrestrial orchid) - Endangered species determination - final. DEC (NSW), Sydney.