Banksia integrifolia  L.f. 1782

pronounced: BANKS-ee-uh in-teg-rih-FOH-lee-uh

(Proteacrae – the waratah family)

common name:  Banksia, Coast Banksia

Banksia banksia fruiting conewas named for Sir Joseph Banks (1743–1820), the botanist on Captain Cook’s first voyage of discovery, credited with the introduction to the Western world of  Eucalyptus, Acacia, Mimosa, and this genus; integrifolia is from two Latin words, integer, whole, entire, and folium, a leaf.

I was surprised to find this tree growing on Magnetic Island, as I have always associated it with more southern climes.

This is a genus of around 170 species, easily recognized by their characteristic flower spikes and fruiting ‘cones’ and heads. They range in size from prostrate woody shrubs to trees up to 30 m tall. They are found in a wide variety of landscapes, sclerophyll forest, (occasionally) rainforest, shrubland, and some more arid landscapes, though not in the Australian deserts. They are heavy producers of nectar, and form a vital part of the food chain in the Australian bush.

This Banksia, one of the most widely distributed, occurs naturally along the east coast of Australia between Victoria and Central Queensland in a broad range of habitats, from coastal dunes to mountains. It is highly variable in form, but is most often encountered as a tree of anything up to 25 m tall. In more exposed areas it may grow as a small, gnarled tree up to about 5 m, and in highly exposed positions, as on exposed coastal headlands, it may be reduced to a small shrub. Its leaves have dark green upper surfaces, but are almost white underneath, a contrast that can be striking on a windy day. They occur in whorls of 3 to 5, and the adult leaves have entire margins. Juvenile leaves have dentate margins with a few short teeth, and are generally larger than adult leaves.

The flowers occur in Banksia’s characteristic ‘flower spike’, an inflorescence made up of several hundred flowers densely packed in a spiral around a woody axis. This is roughly cylindrical, 10–12 cm high and 5 cm in diameter. Flowers are usually pale yellow to yellow, but may be greenish or pink in bud. Each individual flower consists of a tubular perianth made up of 4 united tepals and one long wiry style. The style ends are initially trapped inside the upper perianth parts, but break free as the flowers open. The process starts with the flowers at the bottom of the inflorescence, sweeping up the spike at an unusually high rate of between 100 and 400 flowers per 24 hours. After flowering, the old flower parts wither and fall away over a period of several months, revealing the ‘cone’, a woody axis embedded with many small follicles. These are originally greenish and downy, but gradually fade to dark grey. Each follicle contains a seed, or sometimes 2 separated by a thin woody separator. The seed is black, a little under 1 mm long, with a feathery black wing 1–2 cm long.

Banksia integrifolia was first collected at Botany Bay by Banks and Solander on 29th April, 1770, but not published until 1782, when Linnaeus described the 4 species they had discovered in his Supplementum Plantarum. He distinguished the species by their leaf shapes, and named them accordingly – hence the specific of this one. There followed 200 years of confusion over the taxonomic limits of the species, until the publication in 1981 of Alex George’s book The genus Banksia L.f. Three subspecies of Banksia integrifolia are currently recognized: ssp. integrifolia, ssp. compar, and ssp. monticola.

The heartwood of Banksia integrifolia is pinkish to red, useful for ornamental turnery. It is occasionally used for cabinet-making, and in panelling where a red-coloured, ray-blazoned timber is required.

Larvae of the moth Acmotoma magniferella use this tree as a food plant.


Supplement of Plants


 Photographs taken in Nelly Bay, 2010

Page last updated 13th March 2018

 

 

 

 

 

 

 

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