Allocasuarina, commonly known as sheoak[4]orshe-oak,[5] is a genus of flowering plants in the family Casuarinaceae and is endemic to Australia. Plants in the genus Allocasuarina are trees or shrubs with soft, pendulous, green branchlets, the leaves reduced to scale-like teeth. Allocasuarinas are either monoeciousordioecious, the flowers never bisexual. Male and female flowers are arranged in spikes, the female spikes developing into cone-like structures enclosing winged seeds.
| Allocasuarina | |
|---|---|
| |
| Allocasuarina decaisneanainCentral Australia | |
Scientific classification 
| |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Fagales |
| Family: | Casuarinaceae |
| Genus: | Allocasuarina L.A.S.Johnson[1] |
| Type species | |
| Allocasuarina torulosa (Aiton) L.A.S.Johnson[2][3]
| |
| Species | |
|
61 species; see text. | |
The genera Allocasuarina and Casuarina are similar, and many formerly in the latter now included in Allocasuarina.
Plants in the genus Allocasuarina are trees or shrubs with soft, pendulous, green branchlets, the leaves reduced to 4 to 14 scale-like teeth arranged around in whorls around ribbed, jointed branchlets. Allocasuarinas have separate male and female flowers, sometimes on one plant (monoecious), otherwise on separate male and female plants, (dioecious). Male flowers are arranged in spikes along branchlets that are usually different from the vegetative branchlets. Female flowers are in spikes on short side-branches, the female spikes later developing into cone-like structures enclosing winged seeds known as samaras.[3][4][5][6][7][8][9]
The genera Allocasuarina and Casuarina are similar, many formerly in the latter now included in Allocasuarina. There are 6 to 20 scale-like teeth in each whorl of casuarina leaves and the samaras are grey or yellowish-brown, the bracteoles of the fruiting cones thin, woody and extend well beyond the cone body. There are 4 to 14 scale-like teeth in each whorl of Allocasuarina leaves and the samaras are reddish-brown to black, the bracteoles thickly woody and extend only slightly beyond the cone body.[9]
The genus Allocasuarina was first formally described in 1982 by Lawrence Johnson in the Journal of the Adelaide Botanic Gardens.[2] In the same paper, Johnson transferred some species previously included in Casuarina to the new genus, and nominated Allocasuarina torulosa Aiton L.A.S.Johnson as the type species.[3] The name Allocasuarina means "other Casuarina".[10] ("Allo-" in Greek means "other".)[11]
The following is a list of Allocasuarina accepted by the Australian Plant Census and Plants of the World Online as of April 2023:[12][13]
Plants in the genus Allocasuarina usually grow in nutrient-deficient soils and are endemic to southern Australia, but 4 species occur in north-eastern Queensland, and one in the north of Western Australia.[7]
