Banksia speciosa

Large shrub or small tree in the family Proteaceae found on the south coast of Western Australia

Banksia speciosa, commonly known as the showy banksia, is a species of large shrub or small tree in the family Proteaceae. It is found on the south coast of Western Australia between Hopetoun (33°57′ S) and the Great Australian Bight (approximately 33° S 130° E), growing on white or grey sand in shrubland. Reaching up to in height, it is a single stemmed plant that has thin leaves with prominent triangular "teeth" along each margin, which are long and wide. The prominent cream yellow flower spikes known as inflorescences appear throughout the year. As they age they develop up to 20 follicles each that store seeds until opened by fire. Though widely occurring, the species is highly sensitive to dieback and large populations of plants have succumbed to the disease. Collected and described by Robert Brown in the early 19th century, B. speciosa is classified in the series Banksia within the genus. Its closest relative is B. baxteri. B. speciosa plants are killed by bushfire, and regenerate from seed. The flowers attract nectar and insect feeding birds, particularly honeyeaters, and a variety of insects. In cultivation, B. speciosa grows well in a sunny location on well drained soil in areas with dry summers. It cannot be grown in areas with humid summers, though it has been grafted onto Banksia serrata or B. integrifolia.

[[File:Banksia speciosa map. png|thumb|right|Distribution of B. speciosa (showy banksia), shown on a map of Western Australia's biogeographic regions. from East Mount Barren in the Fitzgerald River National Park and the vicinity of Hopetoun eastwards to Israelite Bay, generally within of the coast. The range extends inland to Mount Ragged and southwest of Grass Patch. There is an outlying population to the east at Point Culver on the Great Australian Bight. Flower spikes appear to have similar numbers of follicles regardless of the age of the parent plant. Young plants begin flowering three years after regenerating from bushfire and store progressively larger numbers of old flowerheads (and hence seed) in the canopy. In one study, decade old plants averaged around 3.5 old cones, whereas 21 year old plants had 105, and were calculated as having over 900 viable seeds per plant. Plants appear to have a life span of at least 40 years, as healthy and vigorous individuals of this age are known. B. speciosa is extremely sensitive to dieback caused by Phytophthora cinnamomi and numbers in Cape Le Grand and Cape Arid National Parks have been drastically reduced as whole populations of plants have perished after exposure. Nursery plants in Italy perished from root and basal stem rot from the pathogen Phytophthora taxon niederhauserii. The tiny sac fungus Phyllachora banksiae subspecies westraliensis has been described from the leaves of B. speciosa, its sole host. This fungus manifests as round flat cream coloured spots around 1–3 mm in diameter on the upper leaf surface. The surrounding leaf tissue is sometimes discoloured orange. One or two shiny black fruit bodies measuring around 0.25–0.75 by 0.25–1 mm appear in the centre of the spots.

A fast growing and attractive plant, B. speciosa grows readily in a sunny location in dry climates on well drained soil, but does poorly in areas of humid summer climate, such as Australia's east coast. It has been grafted successfully onto Banksia serrata and B. integrifolia to enable cultivation in these areas. Seeds do not require any treatment, and take 27 to 41 days to germinate. A specimen flowered in a greenhouse in the Royal Botanic Garden Edinburgh in 1830.