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Showy banksia (Banksia victoriae)

Description

Banksia speciosa grows as a shrub or small tree anywhere from 1 to 6 or rarely 8 m (4–26 ft) high. It has an open many-branched habit, arising from a single stem or trunk with smooth grey bark. Unlike many banksias, it does not have a lignotuber. The plant puts on new growth, which is covered in rusty-coloured fur, in summer. The long thin leaves are linear, 20–45 cm (8–18 in) long and 2–4 cm (0.8–1.6 in) wide. They are bordered with 20 to 42 prominent triangular lobes that have a zigzag pattern. The lobes are 1–2 cm (0.4–0.8 in) long and 1–2.5 cm (0.4–1 in) wide, while the V-shaped sinuses between intrude almost to the midrib of the leaf. The leaf margins are slightly recurved. On the underside of each lobe, there are 3–10 nerves converging on the lobe apex. The midrib is raised on the leaf undersurface; it is covered with white hair when new but brownish hair when mature. The cream to yellow flower spikes, known as inflorescences, can appear at any time of year. They arise on the ends of one- or two-year-old stems and are roughly cylindrical in shape with a domed apex, measuring 4–12 cm (1.6–4.7 in) high and 9–10 cm (3.5–3.9 in) wide at anthesis. Each is a compound flowering structure, with a large number of individual flowers arising out of a central woody axis. A field study on the southern sandplains revealed an average count of 1369±79 on each spike. The perianth is grey-cream in bud, maturing to a more yellow or cream. The style is cream and the tip of the pollen-presenter maroon. Ageing spikes are grey, with old flowers remaining on them, and develop up to 20 large red follicles each. Roughly oval and jutting out prominently from the spike, each follicle is 3.5–5 cm (1.4–2.0 in) long by 2–3 cm (0.8–1 in) wide and 2–3 cm (0.8–1 in) high and is covered in dense fur, red-brown initially before aging to grey. It remains closed until opened by bushfire, and contains one or two viable seeds. The seed is 3.7–4.5 cm (1.5–1.8 in) long and fairly flattened, and is composed of the seed body proper, measuring 1–1.4 cm (0.4–0.6 in) long and 0.9–1.2 cm (0.4–0.5 in) wide, and a papery wing. One side, termed the outer surface, is grey and the other is dark brown; on this side the seed body protrudes and is covered with tiny filaments. The seeds are separated by a 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. It measures 3.7–4.5 cm (1–2 in) long and 2–2.5 cm (0.8–1 in) wide. The dull green cotyledons of seedlings are wider than they are long, measuring 1.4–1.5 cm (0.6 in) across and 1.2–1.3 cm (0.5 in) long, described by Alex George as "broadly obovate". Each cotyledon has a 2 mm (0.08 in) auricle at its base and has three faint nerve-like markings on its lower half. The hypocotyl is smooth and red. The seedling leaves emerge in an opposite arrangement and are deeply serrated into three triangular lobes on each side. The seedling stem is covered in white hair. A variant from the Gibson area has an upright habit and leaves. Otherwise, Banksia speciosa shows little variation across its range. Combined with its vigour and prominence in its habitat, this has led George to speculate that it is a recent development among its relatives. Banksia baxteri resembles B. speciosa and co-occurs with it at the western edge of its range, but has shorter, wider leaves with larger lobes, shorter flower spikes and is a smaller, more open shrub.

Taxonomic tree

  • Domain: Eukarya

    • Kingdom: Plantae

      • Phylum:

        • Class: Magnoliopsida

          • Order: Proteales

            • Family: Proteaceae

              • Genus: Banksia