Banksia is a genus of around 170 species of flowering plants in the family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes and woody fruiting "cones" and heads.
Description
Banksias grow as trees or woody shrubs. Trees of the largest species, B. integrifolia (coast banksia) and B. seminuda (river banksia), often grow over 15 metres tall, with some reaching 30 metres. Shrub species are usually erect, though several species are prostrate, with branches that grow on or below the soil.
Leaves vary greatly between species, from the narrow, 1–1.5 cm long needle-like leaves of B. ericifolia (heath-leaved banksia) to the very large leaves of B. grandis (bull banksia), which may be up to 45 cm long. Most species have serrated leaf edges.
The flowers are arranged in spikes or capitate flower heads. A single flower spike generally contains hundreds or even thousands of flowers; the most recorded is around 6,000 on inflorescences of B. grandis. Flowers are usually a shade of yellow, but orange, red, pink, and violet flowers also occur.
The fruit of Banksia is a woody follicle embedded in the axis of the inflorescence. In many species, the resulting structure is a massive woody structure commonly called a cone. Each follicle usually contains one or two small seeds, each with a wedge-shaped papery wing.
Taxonomy
Specimens of Banksia were first collected by Sir Joseph Banks and Daniel Solander, naturalists on the Endeavour during Lieutenant James Cook's first voyage to the Pacific Ocean. Cook landed on Australian soil on 29 April 1770 at Botany Bay. Four species were present in this first collection: B. serrata (saw banksia), B. integrifolia (coast banksia), B. ericifolia (heath-leaved banksia), and B. robur (swamp banksia).
The genus was formally described and named by Carolus Linnaeus the Younger in April 1782 in Supplementum Plantarum, naming it in honour of Joseph Banks.
Distribution and Habitat
All but one of the living Banksia species are endemic to Australia. The exception is B. dentata (tropical banksia), which occurs throughout northern Australia and on islands to the north including New Guinea and the Aru Islands. An extinct species, B. novae-zelandiae, was found in New Zealand.
Southwest Western Australia is the main centre of biodiversity; over 90% of all Banksia species occur only there. Eastern Australia has far fewer species but includes some of the best known and most widely distributed species, including B. integrifolia and B. spinulosa (hairpin banksia).
Ecology
Banksias are heavy producers of nectar, making them an important food source for nectivorous animals, including honeyeaters, bats, rodents, possums, stingless bees, and a host of invertebrates. Many of these animals play a role in pollination.
About half of Banksia species are killed by bushfire but regenerate quickly from seed, as fire stimulates the opening of seed-bearing follicles. The remaining species survive bushfire by resprouting from a woody base known as a lignotuber or from epicormic buds protected by thick bark.
A significant threat to Banksia is the water mould Phytophthora cinnamomi, commonly known as "dieback," which attacks the roots of plants. All Western Australian species are vulnerable, although most eastern species are fairly resistant.
Uses
Banksias are popular garden plants in Australia due to their large, showy flower heads and the large amounts of nectar they produce. Several species are grown commercially for the cut flower industry, including B. coccinea (scarlet banksia), B. baxteri, B. hookeriana, and B. prionotes (acorn banksia). Banksia wood is occasionally used for ornamental purposes in woodturning and cabinet paneling.
Indigenous peoples of south-western Australia would suck on the flower spikes to obtain nectar and soaked them in water to make a sweet drink. The Noongar people used infusions of the flower spikes to relieve coughs and sore throats.
Cultural References
Perhaps the best known cultural reference to Banksia is the "big bad Banksia men" of May Gibbs' children's book Snugglepot and Cuddlepie, modelled on the appearance of aged Banksia "cones" with follicles for eyes and other facial features.
In 1989, the Banksia Environmental Foundation was created to support and recognise people and organizations that make a positive contribution to the environment. In June 2023, the exoplanet WASP-19b was named "Banksia" in the third NameExoWorlds competition.
