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Tetratheca neglecta

Black-eyed Susan

Family: Elaeocarpaceae

A soft-wooded shrub, to about 60 cm high, with cylindrical to 4-angled stems, with a mixture of short and long hairs.

It occurs mainly around the Greater Sydney area; from north-west of Katoomba and at Richmond, extending south and south-west passed Lake Burragorang and through Sydney, to the Southern Highlands, as far south to near Berry.

It grows in sandy heath, shrubland as well as dry sclerophyll woodland and forest on sandstone and sandy soils.

In Tetratheca spp., leaves are simple and can be arranged alternately or in opposite pairs or whorls. Some species can exhibit varying leaf arrangements (dimorphic).

In this species, leaves are in whorls of 4 to 6, sometimes fewer at the bases of the stems, to 20 mm long, usually less than 1 mm wide, with margins rolled down.

Tetratheca spp. tend to produce solitary or paired flowers in leaf axils, well beyond the foliage. They typically have 4 petals which resemble an even cross (some flowers can have 5 petals), with 8 stamens and 1 carpel. Flowers often point downwards (pendent) which attracts certain insects.

In this species, flowers are solitary, deep lilac-pink, to about 20 mm across, occurring mostly August to November.

Tetratheca spp. produce fruit as capsules which open longitudinally.

In this species, the capsules are to 6 mm long, with seeds to 4 mm long, brown in colour with fine hairs.

In the garden

This species is not known to be cultivated widely and not a lot of information is available at the time of this publication. It may be difficult to grow or may need to be trialled further. Check with local native nurseries for availability. It grows naturally in sandy soils and so may need similar garden conditions to thrive. 

It has been photographed at Sylvan Grove Native Garden in Bankstown.

Some Tetratheca spp. are cultivated commonly, especially T. thymifolia and they make very attractive additions to gardens.

Plant them along open borders or in rockeries for best affect, with well-drained soils and some shade during the warmer months.

Propagation

Propagation can be carried out from seed but this is rarely available.

Cuttings of hardened, current season’s growth usually strike fairly-readily. Cuttings of young suckering shoots will also work well provided the propagation mix is well-drained. The use of a root-promoting hormone is advised for greater success. Cuttings are best done from November to April.

Other information

Tetratheca comprises around 50 to 60 species, endemic to Australia. They occur in all states with the exception of the Northern Territory.

The flower colours have given rise to the common name for many species of “Black-eyed Susan”. However, note that this common name also applies to several exotic species.

Most Tetratheca spp. would die in a fire and regenerate from the seed bank.

Tetratheca – Ancient Greek – tetra meaning “four”, and theke meaning “sac or box”, relating to the condition of the stamens in the flowers which have four lobes or cells.

neglectafrom the Latin ‘neglectus’ meaning previously neglected, likely referring to the condition that this species was not formally recognised until 1976 by botanist Joy Thompson.

This species is not considered to be at risk of extinction in the wild.

NSW Flora online (PlantNET) Tetratheca neglecta profile page:

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

Wikipedia – Tetratheca profile page

https://en.wikipedia.org/wiki/Tetratheca

The Family Tremandraceae – APS NSW

https://austplants.com.au/resources/Documents/South-East-Documents/Articles_About_Plants_and_Gardens/The_Family_Tremandraceae_John_Knight.pdf

By Jeff Howes, edited Dan Clarke