Banksia saxicola
| Banksia saxicola | |
|---|---|
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| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| Order: | Proteales |
| Family: | Proteaceae |
| Genus: | Banksia |
| Species: | B. saxicola |
| Binomial name | |
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Banksia saxicola A.S.George |
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Banksia saxicola, commonly known as the rock banksia or Grampians banksia, is a species of tree or shrub in the plant genus Banksia. It occurs in Victoria in two distinct populations, one in The Grampians and the other on Wilsons Promontory. It has leathery green leaves and grey-yellow flower spikes which appear in summer and early autumn.
Banksia saxicola grows as a tall upright tree to 13 metres (43 ft) high at Wilsons Promontory, or as a sprawling shrub in the Grampians. At the latter location, plants maintain their spreading habit even in more sheltered parts, reaching around 5 metres (20 ft) high there but restricted to 2 metres (7 ft) high in more exposed areas. The leathery dark green leaves are roughly oval and measure 4 to 10 centimetres (2 to 4 in) long by 1 to 3.5 centimetres (0.39 to 1.4 in) wide. They are arranged in whorls along the stems. The flowering period is from January to March, the cylindrical flower spikes, known as inflorescences, arising from two- to six-year-old branches. They are 3.5 to 8 centimetres (1.4 to 3.1 in) high and 5 to 6 centimetres (2 to 2 in) wide at anthesis. Flower parts fall off the ageing spikes, leaving them bare. They swell and develop 20 to 60 follicles that are covered in fine fur and open only when burnt in fire.
Long held to be a form of Banksia integrifolia, Banksia saxicola was formally described by Alex George in his 1981 monograph of the genus Banksia. The species name is derived from the Latin words saxum "rock" and verb cŏlo "inhabit" or "grow in". The type specimen was collected from the summit of Mount William in the Grampians on 17 February 1977.
George concluded it was most closely related to Banksia canei.
B. saxicola's placement within Banksia may be summarised as follows:
Since 1998, American botanist Austin Mast and co-authors have been publishing results of ongoing cladistic analyses of DNA sequence data for the subtribe Banksiinae, which then comprised genera Banksia and Dryandra. Their analyses suggest a phylogeny that differs greatly from George's taxonomic arrangement. Banksia saxicola resolves a sister to B. marginata within the series Salicinae. A 2013 molecular study by Marcel Cardillo and colleagues using chloroplast DNA and combining it with earlier results reaffirmed B. saxicola and B. marginata as each other's closest relatives, and that B. integrifolia was the next closest relative.
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