Triunia is a genus of medium to tall shrubs or small trees found as understorey plants in rainforests of eastern Australia. Members of the plant family Proteaceae, they are notable for their poisonous fleshy fruits or drupes. Only one species, T. youngiana, is commonly seen in cultivation.

Triunia
Scientific classification e
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Proteales
Family: Proteaceae
Subfamily: Grevilleoideae
Tribe: Roupaleae
Genus: Triunia
Johnson & Briggs (1975)[1]
Type species
Triunia youngiana

TaxonomyEdit

Lawrie Johnson and Barbara G. Briggs described the genus Triunia in their 1975 monograph "On the Proteaceae: the evolution and classification of a southern family".[2] The group of species in this genus was previously recognised as a subgenus, Macadamiopsis, of Helicia by Hermann Sleumer in 1955.[3] T. youngiana was made the type species. This plant had originally been described in 1864 as Helicia youngiana before being transferred to the genus Macadamia.

They initially placed the genus in its own subtribe, Triuniinae, within the tribe Helicieae.[4] More recently, the genus has placed in the tribe Roupaleae,[5] Its closest relative is Eucarpha,[6] from New Caledonia.

SpeciesEdit

DescriptionEdit

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 racemes. Flowers are followed by small round red fruit, which are highly toxic.[4] The seeds are round.[5]

Habitat and ecologyEdit

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. They grow in uplands and mountains rainforests,[3] where they form part of the understorey.[4] Two species grow naturally in south-eastern Queensland and one of them grows further southwards through to north-eastern New South Wales.[3] Two other species are only known to grow about 1,500 km (930 mi) to the north in the uplands and mountains rainforests of the Wet Tropics region of north-eastern Queensland.[3]

CultivationEdit

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.[4]

ReferencesEdit

  1. ^ a b "Triunia%". Australian Plant Name Index (APNI), Integrated Botanical Information System (IBIS) database (listing by % wildcard matching of all taxa relevant to Australia). Centre for Plant Biodiversity Research, Australian Government. Retrieved 3 Jan 2014.
  2. ^ Johnson, Lawrie A. S.; Briggs, Barbara G. (1975). "On the Proteaceae: the evolution and classification of a southern family". Journal of the Linnean Society of London. Botany. 70 (2): 83–182. doi:10.1111/j.1095-8339.1975.tb01644.x.
  3. ^ a b c d Foreman, Don B. (1995). "Triunia". In McCarthy, Patrick (ed.). Flora of Australia: Volume 16: Eleagnaceae, Proteaceae 1 (online version). Flora of Australia series. CSIRO Publishing / Australian Biological Resources Study. pp. 404–07. ISBN 978-0-643-05692-3. Retrieved 3 Jan 2014.
  4. ^ a b c d Wrigley, John; Fagg, Murray (1991). Banksias, Waratahs and Grevilleas. Sydney: Angus & Robertson. pp. 543–45. ISBN 0-207-17277-3.
  5. ^ a b Weston, Peter H.; Barker, Nigel P. (2006). "A new suprageneric classification of the Proteaceae, with an annotated checklist of genera" (PDF). Telopea. 11 (3): 314–344.
  6. ^ 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.
  7. ^ Foreman, Don B. (1987). "New species of Xylomelum Sm. and Triunia Johnson & Briggs (Proteaceae)" (PDF). Muelleria. (Online page archive version, link via APNI Triunia ref's). 6 (5). p. 302–305, fig. 3. Retrieved 3 Jan 2014.
  8. ^ a b Foreman, Don B. (1986). "A new species of Helicia, new combinations and lectotypification in Triunia (Proteaceae) from Australia" (PDF). Muelleria. (Online page archive version, link via APNI Triunia ref's). 6 (3). pp. 195–96, fig. 1. Retrieved 3 Jan 2014.