A shrub reaching a height of two metres with multiple stems arising from a lignotuber (swollen root mass).
Bark is smooth and the branchlets are covered with tangled, rusty hairs. The leaves are large, with toothed margins, glossy green above and light green beneath.
The inflorescences of Banksias are generally referred to as spikes or a spike-like structure which consists of fused racemes of paired flowers (hence it gets referred to as a conflorescence). There can be 100s of flowers in each spike. The flowers of banksias have 4 tepals (petals or sepals) in a tubular formation, 4 anthers hidden inside and an elongated carpel (female part) where the style extends outwards forming the edge of the spike (somewhat similar to individual grevillea and hakea flowers).
In this species, large flower spikes (to 20 cm long by 5 cm wide) carry tightly packed metallic green flowers. In bud they are bluish green. Spikes persist after they dry for many months. They appear from January to July. Flower spikes are carried terminally or along older branches. Terminal flower spikes are held above rosettes of the large leaves.
The spike then turns into a cone-like structure of follicles; a fruit which splits open on one side. Each follicle has one or two winged seeds which is actually a fruit in itself called a samara. The follicles can take a long time to mature and open, usually needing a fire. Each “cone” can produce a fair amount of seed with this species having up to 50 follicles per “cone”, each up to 20 mm long.
Banksia robur is a native of the Central and North Coasts of NSW and Southern Queensland where it is found in permanently damp sites such as wet heath and shrubland. In these sites, they are often the most visible plants.
As the common name implies this species is usually found in permanently moist situations.
In the garden plants will thrive in well drained situations as long as they are adequately watered. Perhaps in these situations gardeners should take out some “polypipe insurance”. When planting place a 30 centimetre length of polypipe in the planting hole with half the pipe buried beside to plant. During watering fill the pipe a few times. This directs the water directly to the roots. We use this watering system with all our banksias.
It is known to be successfully cultivated and makes a nice addition to a garden. Give it room to spread out in full sun.
Propagate from seed. B. robur is said to flower 3-5 years from seed.
The last image of this profile shows a red leaf form which is being grown at the Banksia garden in the Australian National Botanic Gardens in Canberra – rather unusual!
Can regenerate from seed bank after fire very readily, as well as, epicormic shoots and a lignotuber below ground.
Banksia is a now a genus of about 170 species (with the inclusion of the genus Dryandra) occurring in Australia but also 1 species in New Guinea and the Aru Islands Regency. NSW currently has about 16 species.
Banksia – named in honour of Joseph Banks (1743 – 1820), famous naturalist and botanist on the Endeavour and other expeditions, and President of the Royal Society for over 40 years. The genus was named in his honour by Linnaeus filius (Carl von Lynne – the Younger, son of the famous Carl von Lynne (Linneaus)).
robur – Latin meaning “strength” which may refer to the robust nature of the plant or its large leaves.
This species is not considered to be at risk of extinction in the wild.
NSW Flora Online (PlantNET) – Banksia robur profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Banksia~robur
Gardening with Angus – Banksia robur profile page https://www.gardeningwithangus.com.au/banksia-robur-swamp-banksia/
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.