Banksia spinulosa

Hairpin Banksia

Family: Proteaceae

Typically, a multi-stemmed shrub to 3 m tall, bearing a lignotuber.

It grows mostly on the central and south coast subdivisions of NSW, extending into the tablelands where records are fewer, also extending up the north coast into Queensland, with disjunct populations up to about Townsville.

It is a common shrub on sandstone outcrop and sandy soils, as well as other soil types like volcanic-clay based soil in some areas (eg: Port Stephens) in dry sandstone ridgetop woodland, gully woodland and forest, as well as coastal heath and shrubland. Seldom found on heavy clay soils.

The leaves are alternate, linear to oblanceolate, to 7 cm long and only 0.5 cm wide, green to dark green in colour with variations in toothing of the leaves. However, leaves usually have short spiny teeth. Lower surface is paler and hairy.

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 and extends outwards forming the edge of the spike (somewhat similar to individual grevillea and hakea flowers).
In this species, the spikes are generally to 15 cm long (sometimes longer) and about 6 cm wide, with each flower thin but up to 3 cm long, orange to yellow-orange in colour. The styles (female part of flower) can be a vivid dark red to purple-black and hooked at the apex, which gives this species its common name.

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 100 follicles per “cone”, each up to 25 mm long.


In the garden

A very popular shrub in gardens and many cultivars are available (see below).

Slow growing but will grow consistently if happy and will form a very nice shrub after a few years. May grow to 2 m tall in a garden (although this will take time) so allow some space. Very suitable for sandstone-outcrop gardens. There are also a wide range of smaller forms. Plant in a well-drained soil for best results – sandy to loam.

Most banksias thrive if planted on a slight slope.

Do not apply a high phosphorus fertiliser as Proteaceae are generally sensitive.

Prune after flowering or harvest cut flowers. Can be trained into a denser shape with periodic pruning. Some cultivars have the potential to produce many spikes if creating a dramatic effect.

Susceptible to Phytophthora and any other root rotting fungus.

Propagation

Propagation from seed is very reliable and not too difficult. Cultivars would have to be done form cuttings to be true-to-form.

Other information

This species has historically been a complex with a range of forms and variety exhibited. A PhD study was undertaken by Margaret Stimpson who raised the variety ranks of the complex to separate species:
Banksia collina
– Banksia cunninghamii
– Banksia neoanglica
– Banksia vincentia

Intermediates between all of these taxa still occur.
Common cultivars include ‘Birthday Candles’, ‘Coastal Cushion’, ‘Stumpy Gold’. (see references for further detail)

Can regenerate from seed bank after fire very readily as well as epicormic shoots and a lignotuber below ground.

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)).

spinulosa – Latin for “bearing spines”, referring to the spiny teeth on the leaves

Not considered to be at risk in the wild. Very common.

http://anpsa.org.au/b-spi.html
https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Banksia~spinulosa
https://www.anbg.gov.au/gnp/gnp7/banksia-spinulosa.html
https://www.gardeningwithangus.com.au/banksia-spinulosa-birthday-candles-banksia/
https://www.gardeningwithangus.com.au/banksia-spinulosa-stumpy-gold-banksia/
https://www.gardeningwithangus.com.au/banksia-spinulosa-coastal-cushion-hairpin-banksia/

By Dan Clarke