| Banksia aquilonia | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| Order: | Proteales |
| Family: | Proteaceae |
| Genus: | Banksia |
| Species: | B. aquilonia |
| Binomial name | |
| Banksia aquilonia (A.S.George) A.S.George |
|
Banksia aquilonia is a species of tall shrub or tree in the plant genus Banksia.
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B. aquilonia grows as a tall shrub or small tree up to 8 metres high. It has hard, fissured, grey bark, and elliptic leaves without serrated margins. Flowers occur in Banksia's characteristic "flower spike", an inflorescence made up of hundreds of pairs of flowers densely packed in a spiral around a woody axis. B. aquilonia's flower spike is a pale yellow colour, roughly cylindrical, 6 to 10 centimetres high. It flowers from March to June.[1]
Although the inflorescences are similar to B. integrifolia, the leaves are marked in their differences - the midrib on the leaves' undersides is distinctively covered in short reddish brown hairs and the leaves are spirally arranged rather than in whorls as in all B, integrifolia subspecies. It was these differences that George felt were distinctive enough for it to be considered a separate species to B. integrifolia.[2]
B. aquilonia was first described by Alex George in 1981 as a variety of Banksia integrifolia (Coast Banksia).[3] In 1994 Thiele and Ladiges published a cladistic analysis of Banksia in which this taxon stood out as the only member of B. integrifolia to be both morphologically and geographically distinct from other infraspecific taxa. On this basis they would have liked to promote it to species rank, but did not because their inferred phylogeny suggested that this taxon arose from within B. integrifolia. They were unwilling to render B. integrifolia paraphyletic by promoting this taxon to species rank, and they were equally unwilling to promote all four varieties to species rank, since the others all had significant overlaps in distribution and morphology. Therefore they simply promoted all four to subspecies rank.[4] This case has since been held up as an interesting case study on how the concept of species should be defined, as it presents the problem of "a monophyletic group comprising a paraphyletic basal group of incompletely differentiated geographic forms within which is nested at least one divergent, autapomorphic taxon that invites treatment as a species."[5]
In 1996, George, who has no objection to paraphyletic taxa, promoted it to species rank.[2] Thus its full name with author citation is "Banksia aquilonia (A.S.George) A.S.George". It is placed in subgenus Banksia, section Banksia and series Salicinae. Its placement within Banksia may be summarised as follows:[1]
Despite initially giving it varietal level, George had noted that it had affinities with the then newly described species Banksia plagiocarpa, which it co-occurs with on and near Hinchinbrook Island in north Queensland.[3]
B. aquilonia occurs in coastal areas of northern Queensland from the Mount Finnigan National Park to the Paluma Ranges, in woodland and forest in granitic sand.[1] It grows from near sand dunes to an altitude of 1000 m (3500 ft).[6]
Birds observed visiting the flower spikes include the Bridled Honeyeater, White-cheeked Honeyeater, Eastern Spinebill and Rainbow Lorikeet.[6]
Banksia aquilonia adapts readily to cultivation.