Banksia.
Family Proteaceae > Subfamily Grevilleoideae > Tribe Banksieae.
About 170 species that are all found in Australia.
They are seen in gardens and used as cut flowers.
Most are shrubs with a few prostrate forms or trees to 20 m or more in height.
Many have lignotubers which are thick, woody tubers (modified stems) that can remain alive
underground for years and allow the plants to regrow after fire.
Trees often have twisted trunks and are low-branching.
The grey fissured bark tends to be very thick – another protective feature against fire.
Young branches are densely covered in reddish or grey hairs.
Leaves are alternate, usually in a rough spiral but can be in whorls.
They vary greatly between the species and many have different juvenile and adult leaves.
The leathery adult leaves are from 1 to 45 cm long and up to 10 cm wide.
The blades, with or without petioles, can be linear, elliptic or obovate.
The edge can be entire, toothed to various degrees, lobed or more deeply dissected.
The edges can be flat, wavy or rolled under and the tip round or pointed.
Young leaves can be densely hairy underneath.
Adult leaves may have some hairs on the upper surface and dense to sparse ones underneath.
Inflorescences, near the branch ends, are mostly solitary spikes up to 40 cm high while
others are smaller, globular heads.
Some species have no, or deciduous, bracts at the base while others are have small bracts.
A central woody axis holds up to hundreds of flowers, without stalks, in pairs.
Each pair has small bracts at the base.
Most flowers are yellowish, greenish or orange but darken with age becoming brown or grey.
The 4 tepals are up to 5.5 cm long and have dense hairs externally.
Tepals are initially fused into a tube with the anthers inserted into the tips.
The superior ovary has a single straight or hooked style up to 4 cm long.
As the style grows it splits the tepal tube and frees the stigma and pollen presenter.
These can be indistinguishable from rest of the style or conical or disc-like.
The 4 nectaries at the base of the ovary produce large amounts of nectar.
Fruit are woody follicles that develop from only a few of the flowers in an inflorescence.
Where the styles persist the spike appears hairy.
Each follicle, up to 2.5 cm long, has 1 or 2 flat, winged, seeds.
In many species the follicles require fire to open.
Banksias can be divided into groups based on combinations of whether the styles are straight or curved,
inflorescences a spike or head, the presence or absence of bracts under the flowers and
having leaves scattered or in whorls. There are a few hybrids.
Dryandras, having cone-like inflorescences with bracts among the flowers and follicles, are now
part of the Banksia genus though still often called Dryandras.
J.F.
