''Triunia'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of medium to tall shrubs or small trees found as understorey plants in rainforests of eastern Australia. Members of the plant family

Proteaceae The Proteaceae form a family of flowering plants predominantly distributed in the Southern Hemisphere. The family comprises 83 genera with about 1,660 known species. Together with the Platanaceae and Nelumbonaceae, they make up the order Pro ...

, they are notable for their poisonous fleshy fruits or drupes. Only one species, ''T. youngiana'', is commonly seen in cultivation.

Taxonomy

Lawrie Johnson Lawrence Alexander Sidney Johnson Fellow of the Australian Academy of Science, FAA, (26 June 1925 – 1 August 1997) known as Lawrie Johnson, was an Australian Taxonomy (biology), taxonomic botany, botanist. He worked at the Royal Botanic Garden ...

and Barbara G. Briggs described the genus ''Triunia'' in their 1975 monograph " On the Proteaceae: the evolution and classification of a southern family". The group of species in this genus was previously recognised as a subgenus, ''Macadamiopsis'', of ''

Helicia ''Helicia'' is a genus of 110 species of trees and shrubs, constituting part of the plant family Proteaceae. They grow naturally in rainforests throughout tropical South and Southeast Asia, including India, Sri Lanka, Indochina, Peninsular Mala ...

'' by Hermann Sleumer in 1955. ''T. youngiana'' was made the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

. This plant had originally been described in 1864 as ''Helicia youngiana'' before being transferred to the genus ''

Macadamia ''Macadamia'' is a genus of four species of trees in the flowering plant family Proteaceae. They are indigenous to Australia, native to northeastern New South Wales and central and southeastern Queensland specifically. Two species of the genus ...

''. They initially placed the genus in its own subtribe, Triuniinae, within the tribe Helicieae. More recently, the genus has been placed in the tribe Roupaleae, Its closest relative is ''

Eucarpha ''Eucarpha'' is a genus of flowering plant of the family Proteaceae, endemic to New Caledonia. Two species are recognised. Up to 1975, these were classified within the genus ''Knightia (plant), Knightia'' until Lawrence Alexander Sidney Johnson, ...

'',Sauquet, H., P. H. Weston, C. J. Anderson, N. P. Barker, D. J. Cantrill, A. R. Mast, and Savolainen, V. (2009). Contrasted Patterns of Hyperdiversifaction in Mediterranean Hotspots. Proceedings of the National Academy of Sciences of the USA 106 (1): 221–25. from

New Caledonia ) , anthem = "" , image_map = New Caledonia on the globe (small islands magnified) (Polynesia centered).svg , map_alt = Location of New Caledonia , map_caption = Location of New Caledonia , mapsize = 290px , subdivision_type = Sovereign st ...

Species

*''

Triunia erythrocarpa ''Triunia erythrocarpa'', or spice bush, is a shrub of the family Proteaceae native to Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_ ...

'' – Wet Tropics of north-eastern Qld endemic *''

Triunia montana ''Triunia montana'', or mountain spice bush, is a shrub of the family Proteaceae native to Queensland. References Flora of Queensland montana Montana () is a state in the Mountain West division of the Western United States. It ...

'' – Wet Tropics mountains of north-eastern Qld endemic *''

Triunia robusta ''Triunia robusta'', or glossy spice bush, is a shrub of the family Proteaceae native to Queensland. References Endemic flora of Queensland robusta ROBUSTA (Radiation on Bipolar for University Satellite Test Application) is a nano-satelli ...

'' – south-east Qld restricted endemic *''

Triunia youngiana ''Triunia youngiana'', commonly known as red nut or spice bush, is a shrub of the family Proteaceae native to New South Wales and Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location ...

'' – north-east NSW to south-east Qld endemic (

)

Description

The members of the genus grow as shrubs to small trees, with simple green obovate to elliptical leaves and new growth covered in reddish hairs. The flowers are fragrant and arranged in terminal

raceme A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...

s. Flowers are followed by small round red fruit, which are highly toxic. The seeds are round.

Habitat and ecology

The four species grow naturally only in eastern Australia between Dorrigo in mid-northern New South Wales and the Wet Tropics rainforests region of north-eastern

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

. They grow in uplands and mountains rainforests, where they form part of the

understorey In forestry and ecology, understory (American English), or understorey (Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the forest canopy without penetrating it to any great extent, but abov ...

. Two species grow naturally in south-eastern Queensland and one of them grows further southwards through to north-eastern New South Wales. Two other species are only known to grow about to the north in the uplands and mountains rainforests of the Wet Tropics region of north-eastern Queensland.

Cultivation

In cultivation, all four species grow into garden shrubs with attractive foliage, flowers and fruit, and can tolerate heavy shade to full sun. They require fair to good soil drainage and can be propagated by seed or cutting.

References

{{Taxonbar, from=Q7844607 Proteaceae genera Proteales of Australia Taxa named by Barbara G. Briggs Taxa named by Lawrence Alexander Sidney Johnson Taxa described in 1975