Allocasuarina duncanii, commonly known as Duncan's sheoak,[2] or conical sheoak,[3] is a species of flowering plant in the family Casuarinaceae and is endemic to Tasmania. It is a small dioecious tree that has branchlets up to 200 mm (7.9 in) long, the leaves reduced to scales in whorls of seven to nine, and the fruiting cones 15–60 mm (0.59–2.36 in) long containing winged seeds (samaras) 6–10 mm (0.24–0.39 in) long.
| Allocasuarina duncanii | |
|---|---|
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| In the Royal Tasmanian Botanical Gardens | |
Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Fagales |
| Family: | Casuarinaceae |
| Genus: | Allocasuarina |
| Species: | A. duncanii
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| Binomial name | |
| Allocasuarina duncanii | |
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| Occurrence data from AVH | |
Description
editAllocasuarina duncanii is a small, erect, dioecious tree that typically grows to a height of up to 8 m (26 ft). Its branchlets are up to 200 mm (7.9 in) long, the leaves reduced to scale-like teeth 0.8–1.5 mm (0.031–0.059 in) long, arranged in whorls of seven to nine around the branchlets. The sections of branchlet between the leaf whorls (the "articles") are 4–17 mm (0.16–0.67 in) long and 0.9–1.4 mm (0.035–0.055 in) wide. Male flowers are arranged in head-like spikes 7.5–13 mm (0.30–0.51 in) long, with six to eight whorls per centimetre (per 0.39 in.), the anthers about 1 mm (0.039 in) long. Female cones are cylindrical, on a peduncle 4–10 mm (0.16–0.39 in) long. Mature cones are 15–60 mm (0.59–2.36 in) long and 12–25 mm (0.47–0.98 in) in diameter, the samaras dark brown to black and 6–10 mm (0.24–0.39 in) long.[3][4][5]
This sheoak is similar to A. monilifera that is mostly monoecious, and lacks the "conifer-like" habit of A duncanii.[3]
Taxonomy
editAllocasuarina duncanii was first formally described in 1994 by Lawrie Johnson and Dennis Morris in the journal Telopea from specimens collected near the headwaters of the Nicholls Rivulet in 1993.[4][6] The specific epithet, (duncanii) honours "Mr Fred Duncan", who brought the species to the attention of botanists.[4]
Distribution and habitat
editDuncan's sheoak grows in shallow soil over dolerite, usually at altitudes above 500 m (1,600 ft), on Mount Dromedary, the Wellington Range, Snug Tiers and on South Bruny Island.[2]
Conservation status
editAllocasuarina duncanii is listed as "rare" under the Tasmanian Government Threatened Species Protection Act 1995. The main threats to the species are inappropriate fire regimes, drought and climate change.[2][5]
References
edit- ^ "Allocasuarina duncanii". Australian Plant Census. Retrieved 20 May 2023.
- ^ a b c "SPRAT Profile Allocasuarina duncanii - Duncan's sheoak". Australian Government Department of Climate Change, Energy, the Environment and Water. Retrieved 24 May 2023.
- ^ a b c "Allocasuarina duncanii". Tasmanian Government Department of Primary Industries, Parks, Water and Environment. Retrieved 24 May 2023.
- ^ a b c Johnson, Lawrence A.S.; Morris, Dennis I. (1994). "Allocasuarina duncanii, a new species in Allocasuarina section Cylindropitys (Casuarinaceae)". Telopea. 5 (4): 793–794. Retrieved 25 May 2023.
- ^ a b "Allocasuarina duncanii (Allocasuarinaceae) Duncan's she-oak". Hobart District Group of The Australian Plants Society - Tasmania Inc. Archived from the original on 11 May 2008. Retrieved 24 January 2017.
- ^ "Allocasuarina duncanii". APNI. Retrieved 25 May 2023.