A compact shrub, usually to 0.6 m high, spreading to about 0.5 metres wide with many stems.
It is endemic to NSW; growing mainly on the central tablelands / coastal divide, with concentrated records as far north as Newnes Plateau, south through Lithgow and east to Kurrajong-area, south to Katoomba and Lake Burragorang. There are outlying records further north; east of Rylestone near Mt Coricudgy, and as far south as Braidwood and Mogo State Forest.
It is mainly found in dry sclerophyll woodland and forest, into heathland and shrubland, mainly on sandstone substrate.
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 usually in whorls of 5 to 7, sometimes in pairs or lesser numbers on lower parts of the branches, to 15 mm long, about 1 mm wide, linear in shape, upper surface densely hairy 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 in October to November.
Tetratheca spp. produce fruit as capsules which open longitudinally. In this species, the capsules are to 5 mm long and opening longitudinally; seeds about 3 mm long.
Cultivation information for this species is very scant. Check with native nurseries for availability. It is one of the more rarer species in NSW and so may not be commonly cultivated.
It grows naturally on shallow, well-drained soils derived from sandstone, so consider similar conditions when planting in a garden.
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 can be carried out from seed but this is rarely available. Cuttings of hardened, current season’s growth usually strike fairly readily. The use of a root-promoting hormone seems advantageous.
Tetratheca comprises around 50 to 60 species, endemic to Australia. They occur in all states with the exception of the Northern Territory. NSW currently has 16 species.
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.
rubioides…resembling the genus Rubia – a genus of plants known as “Madders“; the species of which have been used for centuries in India, Asia and Europe.
This species is not considered to be at risk of extinction in the wild.
NSW Flora Online (PlantNET) –Tetratheca rubioides profile page: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Tetratheca~rubioides
Plants of South Eastern Australia (LUCID Online Plant Identification Website/App) – Tetratheca rubioides profile page https://apps.lucidcentral.org/plants_se_nsw/text/entities/tetratheca_rubioides.htm