Silver banksia (Banksia marginata)

Description

Banksia marginata, commonly known as the Silver Banksia, is a species of tree or woody shrub in the plant genus Banksia found throughout much of southeastern Australia. It ranges from the Eyre Peninsula in South Australia, to north of Armidale, New South Wales, and across Tasmania and the islands of Bass Strait. It grows in various habitats, including Eucalyptus forest, scrub, heathland and moorland. Banksia marginata varies widely in habit, ranging from a small shrub, 20 cm (7.9 in) high, to a large tree, 12 m (40 ft) tall. The narrow leaves are linear and the yellow inflorescences (flower spikes) occur from late summer to early winter. The flower spikes fade to brown and then grey and develop woody follicles bearing the winged seeds. Originally described by Antonio Jos- Cavanilles in 1800, further collections of B. marginata were described as several separate species by Robert Brown in 1810. However, all were reclassified as a single species by George Bentham in 1870. No distinct subspecies have been recognised by Banksia expert Alex George, who nonetheless concedes that further work is needed. Banksia marginata is a highly variable species, usually ranging from a small shrub around a metre (3 ft) tall to a 12-metre-high (39 ft) tree. Unusually large trees of 15 to possibly 30 m (50–100 ft) have been reported near Beeac in Victoria's Western District as well as several locations in Tasmania, while compact shrubs limited to 20 cm (7.9 in) high have been recorded on coastal heathland in Tasmania (such as at Rocky Cape National Park). Shrubs reach only 2 m (6.6 ft) high in Gibraltar Range National Park. The bark is pale grey and initially smooth before becoming finely tessellated with age. The new branchlets are hairy at first but lose their hairs as they mature, the new growth a pale or pinkish brown. The leaves are alternately arranged on the stems on 2–5 mm long petioles, and characteristically toothed in juvenile or younger leaves (3–7 cm (1.2–2.8 in) long). The narrow adult leaves are dull green in colour and generally linear, oblong or wedge-shaped (cuneate) and measure 1.5–6 cm (0.6–2.4 in) long and 0.3–1.3 cm (0.1–0.5 in) wide. The margins become entire with age, and the tip is most commonly truncate or emarginate, but can be acute or mucronate. The cellular makeup of the leaves shows evidence of lignification, and the leaves themselves are somewhat stiff. Leaves also have sunken stomates. The leaf undersurface is white with a prominent midrib covered in brownish hairs.