Banksia sceptrum

Banksia sceptrum generally grows as a shrub up to 2–4 m (6+1⁄2–13 ft) high, though sometimes it reaches 5 m (16+1⁄2 ft). It is many-branched and can reach 4 m (13 ft) in diameter. The stocky trunk has smooth or mildly tessellated pale grey bark. New growth has been recorded in spring and autumn, and may possibly occur over the summer. New branchlets are covered in fine greenish-brown fur and become smooth and pale grey after around two years.The leaves are roughly oblong-shaped with truncate or emarginate ends and measure 4–9 cm (1+1⁄2–3+1⁄2 in) long and 1–3 cm (3⁄8–1+1⁄8 in) wide. They are on 5–8 mm (1⁄4–3⁄8 in) long petioles. The flat leaf margins have short blunt teeth. The upper and lower surfaces of the leaf are covered in dense fur, but become smooth with age.

The tall flower spikes, known as inflorescences, arise at the ends of vertical branches over November to January, and can be striking in appearance. They take 6–7 months to develop—longer than other members of the genus. Between 7 and 21 cm (3 and 8+1⁄2 in) high and 8–10 cm (3+1⁄4–4 in) wide, they are bright yellow and highly prominent. Flower opening (anthesis) takes place over 1–2 weeks, and proceeds up the flower spike. The ageing flowers turn grey and remain on the spike as the woody oval follicles develop. The infructescence—an old spike bearing follicles—is bulky with a 6–8 cm (2+1⁄4–3+1⁄4 in) diameter. There are up to 50 follicles on each spike, each 1.5–2.5 cm (1⁄2–1 in) long, 0.8–1.8 cm (3⁄8–3⁄4 in) high and 1–1.6 cm (1⁄2–3⁄4 in) wide. When new they are covered with dense grey fur, which wears off exposed areas.

The obovate (egg-shaped) seed is 3–3.5 cm (1+1⁄8–1+3⁄8 in) long and fairly flattened. It is composed of the obovate seed body (containing the embryonicplant), measuring 1.1–1.4 cm (3⁄8–1⁄2 in) long by 0.7–0.9 cm (1⁄4–3⁄8 in) wide, and a papery wing. One side, termed the outer surface, is brown and slightly wrinkled and the other is brown-black and sparkles slightly. The seeds are separated by a sturdy dark brown seed separator that is roughly the same shape as the seeds with a depression where the seed body sits adjacent to it in the follicle. The first pair of leaves produced by seedlings, known as cotyledons, are obovate and measure 1.4–1.5 cm (1⁄2–5⁄8 in) long by 1.2 cm (1⁄2 in) wide. The upper leaf margin of the wedge is crinkled. The auricle at the base of the cotyledon leaf is pointed and measures 0.2 cm (1⁄8 in) long.