Nature conservation

Threatened species

Slaty Leek 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: Prasophyllum fuscum
Conservation status in NSW: Critically Endangered
Commonwealth status: Vulnerable
Gazetted date: 18 Dec 2009
Profile last updated: 12 Aug 2019

Description

An orchid to 45 cm tall with a single leaf to 40 cm long. Inflorescences have 10-30 moderately crowded flowers, which are greenish brown to reddish brown, and lightly scented. Dorsal sepals are up to 9.5 mm long and pointed. Lateral sepals are free and up to 10 mm long and are recurved, parallel, pointed. Petals are 7-7.5 mm long, projecting forward to spreading, pointed. The labellum (median petal) is 8-9 mm long and sharply curved backwards near the middle, constricted and ending in a relatively short midlobe, often slightly crinkled. The callus is shiny, prominently raised, with irregular margins, extending beyond the labellum bend onto the midlobe. Column wings are bright or pale pink. There has been previous confusion regarding the taxonomic status of this species, as it is very similar to P. uroglossum and P. pallens.

Distribution

The type specimen is from "moist meadows towards the Georges River" in the Sydney area. The species is likely to be extinct from this area. Harden (1993) states that it is confined to the Blue Mountains area. However, some authorities believe Prasophyllum species from this area are not P. fuscum, but an undescribed species. In addition, some authorities believe it is identical to P. uroglossum which occurs in the Wingecarribee area.

Habitat and ecology

  • Grows in moist heath, often along seepage lines. The known population grows in moist sandy soil over sandstone amongst sedges and grasses in an area that appears to be regularly slashed by the local council.
  • Flowering does not necessarily occur every year, often skipping years. Although successful flowering and reproduction is likely to be dependent on favourable weather and habitat conditions, the factors which influence flowering behaviour are poorly understood. The seed is dust-like and is wind dispersed.
  • Dies back after the flowering and fruiting phases and exist only as a dormant tuber for much of the year. Like most terrestrial orchids, the species is believed to be semi or fully dependent on a mycorrhizal symbiont.
  • Dormant over summer and leaves emerge around April and flowering occurs from September to December.
  • The response of this species to fire is unknown, however fire stimulation of flowering is common within the genus.
  • Reproduction is by means of seed and probably to a lesser extent by vegetative reproduction. Flowers are not self-pollinating , as not all set seed and the perfume suggests an insect pollinator. The pollinator is unknown, but related species seem to be pollinated by a variety of thynnid wasps and perhaps hoverflies. It can be assumed that there is more than one pollinator species. The mature seeds senesce after seed dispersal in late December and January.
  • The species is very similar to P. uroglossum but has a much shorter midlobe on the labellum and by having the callus extending well onto the midlobe. It has also been confused with P. pallens which can be distinguished by its paler-coloured flowers with a musty smell.
  • The total population, based on a single observation in 2007, is estimated to be approximately 25 mature individuals.

Regional distribution and habitat

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


Threats

Recovery strategies

Activities to assist this species

Information sources

IBRA Bioregion IBRA Subregion Known or predicted Geographic restrictions region
Sydney BasinBurragorang Predicted None
Sydney BasinMoss Vale Known None
Sydney BasinSydney Cataract Predicted None
Sydney BasinWollemi Known None