Zieria involucrata - 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: Zieria involucrata
Conservation status in NSW: Endangered
Commonwealth status: Vulnerable
Gazetted date: 13 Dec 2002
Profile last updated: 01 Dec 2017

Description

A small, erect, sparse shrub, growing 1 – 2 metres in height. Branches and leaves are densely covered with hairs which form a soft, velvety covering (tomentum). When looked at under magnification most hairs appear star-shaped, although simple and two-forked hairs are also present. Leaves are opposite and consist of either a single leaflet or three leaflets, with both forms usually being present on the same branch (occasionally unifoliolate leaves only are present on a branch). Leaflets are dark green above, light grey-green below, oblong to elliptic to lance-shaped, 3 – 6 cm long and 6 – 15 mm wide. The flower clusters, consisting of 3 – 21 flowers, are shorter than the leaves and enclosed in numerous small, leaf-like bracts, 7 – 12 mm long, which are also covered in dense, white hairs. Flowers are white with pink tinges, and slightly hairy.

Distribution

Has a disjunct distribution north and west of Sydney, in the Baulkham Hills, Hawkesbury, Hornsby and Blue Mountains local government areas. Recent records for the species come from 22 populations in the catchments of the Macdonald, Colo and Hawkesbury Rivers between Melon Creek and Mogo Creek in the north to Little Cattai Creek (Hillside) and Wheeny Creek (Colo) in the south and from a single population in the upper Blue Mountains north of Katoomba. In addition, historical records exist for at least two other localities in the eastern Blue Mountains: south of Springwood Valley Heights and north-west of Kurrajong.

Habitat and ecology

  • Occurs primarily on Hawkesbury sandstone. Also occurs on Narrabeen Group sandstone and on Quaternary alluvium.
  • Found primarily in sheltered forests on mid- to lower slopes and valleys, e.g. in or adjacent to gullies which support sheltered forest, although some populations extend upslope into drier vegetation. Also known from at least two atypical ridgetop locations. The canopy typically includes Syncarpia glomulifera subsp. glomulifera (Turpentine), Angophora costata (Smooth-barked Apple), Eucalyptus agglomerata (Blue-leaved Stringybark) and Allocasuarina torulosa (Forest Oak).
  • Ecological knowledge about this species is limited.
  • Flowering usually takes place in spring. Plants usually first flower and set seed 3 – 5 years after germination, but maximum seed production probably does not occur until 6 – 10 years of age.
  • While there is some evidence that individual plants may be capable of resprouting after fire, the species is probably best considered as an obligate seeder that relies on seed germination after disturbance to maintain populations. A soil seedbank, which may last 1 – 2 decades, appears to be established by this species, so for a number of years following fire or other disturbance the species may not be apparent, but be present only as seed in the soil.
  • Either heat or smoke or a combination of these factors may play a role in breaking soil-stored seed dormancy. Both the amount of smoke and the level of heating could influence germination success. A certain level of heat may be optimal for breaking seed dormancy (such that too little heat results in seeds staying dormant, while too much heat kills seeds).

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 BasinCumberland Predicted None
Sydney BasinPittwater Predicted None
Sydney BasinWollemi Known None
Sydney BasinYengo Known None