Placospermum
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Proteales
Family: Proteaceae
Subfamily: Persoonioideae
Tribe: Placospermeae
Genus: Placospermum
C.T.White & W.D.Francis
Species:
P. coriaceum
Binomial name
Placospermum coriaceum
C.T.White & W.D.Francis

Placospermum is a genus of a single species of large trees, constituting part of the plant family Proteaceae.[1][2] The species Placospermum coriaceum is endemic to the rainforests of the wet tropics region of northeastern Queensland, Australia.[2][3][4] Common names include rose silky oak and plate-seeded oak.[4]

History

The genus and species were first formally scientifically described in 1924 by Cyril T. White and William D. Francis.[2][5] The precise relationships of the genus were unclear, though it was clear it was an early offshoot within the Proteaceae and retained primitive characteristics, until Lawrie Johnson and Barbara G. Briggs classified it in the subfamily Persoonioideae in their 1975 monograph "On the Proteaceae: the evolution and classification of a southern family". They noted that it had large chromosomes, like those of Persoonia and allied genera, as well as sharing some other primitive features.[6]

Description

Placospermum coriaceum sapling, Kuranda, Queensland, 27 June 2009

Placospermum coriaceum trees grow to 30 m (100 ft) tall in their native rainforests, and are likely to be much smaller in cultivation. Leaves on the youngest plants are simple and oblanceolate, but large lobed intermediate leaves soon appear. These are up to 90 cm (36 in) long with up to nine lobes up to 20 cm (8 in) long each. The adult leaves are once again simple, and are spathulate or oblanceolate and up to 17 cm (7 in) long and leathery. The pinkish flowers grow in racemes at the end of branches.[7] Flattened oval fruit follow, which measure 3.5-4 by 3 cm. Each contains many seeds.[4] Like other members of the Persoonioideae, Placospermum coriaceum lacks the cluster roots typical of most Proteaceae.[8]

The large lobed immature leaves are an attractive feature, and Placospermum coriaceum has been cultivated as an indoor plant.[7]

References

  1. ^ "Placospermum". Flora of Australia Online. Department of the Environment and Heritage, Australian Government.
  2. ^ a b c White, Cyril T.; Francis, William D. (1924). "Contributions to the Queensland Flora No. 2: Placospermum" (digitised, online, incl. p. 81 illustr.). Proceedings of the Royal Society of Queensland for 1923. 35: 79–81.
  3. ^ "Placospermum coriaceum". Flora of Australia Online. Department of the Environment and Heritage, Australian Government.
  4. ^ a b c F.A. Zich; B.P.M Hyland; T. Whiffen; R.A. Kerrigan (2020). "Placospermum coriaceum". Australian Tropical Rainforest Plants, Edition 8. Commonwealth Scientific and Industrial Research Organisation (CSIRO). Retrieved 5 March 2021.
  5. ^ Weston, Peter H.; Nigel P. Barker (2006). "A new suprageneric classification of the Proteaceae, with an annotated checklist of genera". Telopea. 11 (3).
  6. ^ 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.
  7. ^ a b Wrigley, John; Fagg, Murray (1991). Banksias, Waratahs and Grevilleas. Sydney: Angus & Robertson. pp. 511–12. ISBN 0-207-17277-3.
  8. ^ 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. doi:10.7751/telopea20065733.
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