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Zieria prostrata

Headland Zieria

Family: Rutaceae

A prostrate shrub, only to a few centimetres tall, forming ground-covering mats to 0.5 or more metres.

It has a very restricted distribution, occurring on coastal headlands in NSW, north of Coffs Harbour, between Korora and Woolgoolga.

It is found in low coastal heathlands, usually on sandy soils.

It is a listed threatened species in the wild.

The branches have ridges and are without warts and hairs.

Zieria spp. have leaves arranged in opposite pairs, compound with three leaflets (tri-foliolate) or one leaflet (uni-foliolate). When tri-foliolate, the leaflets are often similar in shape with the middle leaflet often larger, and with leaves usually strongly odorous, green to grey-green.
In this species, the leaves are tri-foliolate, with obovate to elliptic leaflets, up to 20 mm long and to 6 mm wide, mostly hairless and the same colour on both sides; strongly aromatic.

Zieria spp. have flowers arranged in groups (cymose clusters) in the leaf axils and have four sepals joined at the base and four petals, alternating with the sepals. There are four stamens and four fused carpels.
In this species, the flowers are arranged in clusters of mostly 3 to 7 (possibly up to 35) in leaf axils with the clusters usually much shorter than the leaves; white when open (pink in bud) about 5 mm in diameter; occurring in spring and summer.

Zieria have a fruit described as a schizocarp-capsule which splits into segments called cocci (singular coccus).

Fruit generally have four cocci, each containing one or two seeds.

In this species, the cocci are dotted with oil glands and hairless, red-green in colour when forming.

In the garden

This species is commonly propagated and is marketed under cultivar names. It serves very well as a dense groundcover and is useful for rockeries and as a spill-over. It also does well in pots. It is one of the most popular zierias.

Plant in a well-drained soil for best results but it is reported to tolerate heavier soils. Grow in full sun to filtered light. It is reported to be robust against disease. However, it can suffer physical damage easily and should not be walked on once established.

It can be used as a living mulch if established correctly.

Many Zieria make interesting garden plants and deserve a place in gardens. They are a member of the Rutaceae family which include the genera Boronia, Philotheca and Crowea, all of which can be challenging to grow.

Some species are more commonly grown. They require good drainage, preferably on a light sandy soil and a semi-shaded area. They have soft foliage, can be pruned into nice-rounded shrubs and can flower prolifically

Propagation

In common with most members of the Rutaceae, propagation from seed is difficult but cuttings usually strike readily from current season’s growth. This species strikes reliably from cuttings.

Other information

This species is marketed in some nurseries as Zieria ‘Carpet Star’

 Zieria is a genus strongly odoriferous soft-woody shrubs, or small trees, with over 40 species described, all of which are endemic to Australia except for one species which is found in New Caledonia. They occur in all Australian states except Western Australia but the genus is under review and a number of species are yet to be described or the description published.

Zieria are similar to the better known genus Boronia but can be distinguished by the number of stamens in the flowers – four and eight in Boronia.

Most Zieria would die in a bushfire and regenerate from seeds. Suckering from roots may be possible. This species can likely resprout from root suckers.

Zierianamed in honour of Jan Zier (d. 1793), by Sir James E. Smith. Zier was a Polish botanist and cryptogam (ferns, mosses, lichen and fungi) specialist, for which there is little information online. He assisted Jacob Friedrich Ehrhart, the Director of the Botanical Garden of Hannover.

prostrata Latin meaning “prostrate”, referring to the habit of the species.

This species is listed as being threatened with extinction under both State and Commonwealth legislation, with the category of Endangered.

NSW Flora Online (PlantNET) – Zieria prostrata profile page

https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Zieria~prostrata  

Australian National Herbarium – Zieria prostrata profile page https://www.anbg.gov.au/gnp/trainees-2017/zieria-prostrata.html

NSW Office of Environment and Heritage – Zieria prostrata profile page

https://www.environment.nsw.gov.au/threatenedspeciesapp/profile.aspx?id=10863

By Jeff Howes, Warren Sheather, edited Dan Clarke