A common, evergreen, large shrub to small tree, growing to 8 metres tall by several metres wide.
It is found in the coastal regions of NSW, growing north of Bega, commonly along the coast, into Queensland (in disjunct populations) as far north as between Port Douglas and Cape Tribulation.
It is typically found in rainforest – including littoral, sub-tropical, tropical and warm temperate, as well as wet sclerophyll forests and moist forms of dry sclerophyll woodland. It can grow on a range of soils from sandy to enriched loams and shales.
Synoum has compound leaves, arranged alternately and with an odd number of leaflets on each leaf (paired leaflets and then 1 terminal leaflet – which is termed an imparipinnate leaf). In this species, the leaves are to 30 cm long by up to 20 cm wide; leaflets are to 10 cm long and to 3 cm wide, obovate to oblanceolate to broadly elliptic in shape; leaflets can number up to 11, with the terminal one usually largest; somewhat glossy, dark to mid-green in colour (juvenile leaves are usually lighter green); the leaves are generally hairless except for the prominently hairy domatia; very attractive and lush foliage generally.
Synoum has flowers with usually 4 but sometimes 5 petals with 8 stamens and 1 carpel. The flowers are small (dainty), to about 12 mm across, white, sometimes with pink tones, and produced in panicles to about 5 cm long, from the leaf axils.
The fruits are very conspicuous and showy, forming a brown to red-brown capsule with 3 distinct lobes, which are up to 20 mm in diameter and readily recognisable for this species. Inside the capsule are red paired-seeds.
A very nice plant to grow if your garden has some space for it and a small tree is required.
It is a small attractive shade tree that will tolerate a range of soils from sandy to clay.
It has attractive red fruits that are bird attracting as well as sweetly-scented flowers.
It is best grown in a part-shade position on an enriched soil with reliable moisture in dry times.
(This Editor grew two plants at a previous property at Sylvania (Sydney) on a sandy soil. Plants grew consistently, if slowly, without any issue and flowered about two years after planting).
Germination from fresh seed is reliable and relatively fast. Plants are often available from rainforest as well as other native nurseries.
Synoum is a monotypic genus with only one species, endemic to Australia.
There are two subspecies recognised:
• subsp. glandulosum in NSW,
• subsp. paniculosum – which grows form Mackay to Cape Tribulation in Queensland.
The timber of Synoum is used has been used in carpentry and has some resemblance to Rosewood.
This species may be prone to fire in some habitats and likely regenerates from the seedbank. It may also be able to sucker from the base of stems and root stocks.
Synoum – from Ancient Greek which means “fused-eggs” – referring to the 2 joined seeds that are housed in each loculus (compartment) within the capsule. The genus was originally described by French naturalist Adrien-Henri de Jussieu (1797-1853) in 1830.
glandulosum – Latin – glandulosus meaning “glandular”, referring to the glandular nature of the domatia in the leaves.
This species is not considered to be at risk of extinction in the wild.
NSW Flora online (PlantNET) – Synoum glandulosum profile page
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.
Save Our Waterways Now – Synoum glandulosum profile page: