''Acacia polystachya'' is a tree belonging to the genus ''
Acacia
''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus na ...
'' and the subgenus ''Juliflorae'' that is native to north eastern
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
.
Description
The tree typically grows to a height of and has dark brown to grey coloured bark that is smooth of corrugated. It has smooth to pustular, flattened or angular branchlets that are grey, brown or purplish in colour. Like most species of ''Acacia'' it has
phyllode
Phyllodes are modified petioles or leaf stems, which are leaf-like in appearance and function. In some plants, these become flattened and widened, while the leaf itself becomes reduced or vanishes altogether. Thus the phyllode comes to serve the ...
s rather than true leaves. The narrowly elliptic phyllodes are sometimes asymmetrical and straight to sickle shaped. The
glabrous and chartaceous phyllodes are in length and and have two to three prominent nerves. It blooms between April and July producing yellow flowers.
The flower-spikes are in length and are loosely arranged with bands of pale yellow flowers. The thinly coriaceous blackish
seed pods that form after flowering have a linear shape and are straight-sided to slightly and often constricted between seeds and covered in a powdery white coating. The glabrous pods can be strongly curved and irregularly twisted with a length of and . The black and slightly pitted seeds inside the pods are arranged longitudinally and have a discoid shape with a length of with a yellow
funicle surrounding it.
[
]
Taxonomy
The species was first formally described by the botanist Allan Cunningham in 1842 as part of William Jackson Hooker
Sir William Jackson Hooker (6 July 178512 August 1865) was an English botanist and botanical illustrator, who became the first director of Kew when in 1841 it was recommended to be placed under state ownership as a botanic garden. At Kew he ...
's work ''Notes on Mimoseae, with a synopsis of species'' published in the ''London Journal of Botany''. It was reclassified by Leslie Pedley in 1987 as ''Racosperma polystachyum'' then transferred back to genus ''Acacia'' in 2001.
Distribution
It is endemic to the parts of far north and northern Queensland in areas along the east coast. The northern range of the tree extends as far north as Banks Island in the Torres Strait down to along the eastern side of Cape York Peninsula to around Cairns
Cairns (, ) is a city in Queensland, Australia, on the tropical north east coast of Far North Queensland. The population in June 2019 was 153,952, having grown on average 1.02% annually over the preceding five years. The city is the 5th-most-p ...
in the south and has also been found on Palm Island. It is found along beaches and creeks and rivers where it grows in alluvial soils often as a part of vine thicket communities.[
]
See also
* List of ''Acacia'' species
References
{{Taxonbar, from=Q15288378
polystachya
''Polystachya'', abbreviated Pol in horticultural trade, and commonly known as yellowspike orchid, is a flowering plant genus in the orchid family (biology), family (Orchidaceae). This rather distinctive genus was described by William Jackson Hoo ...
Endemic flora of Queensland
Taxa named by Allan Cunningham (botanist)
Plants described in 1842