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''Banksia speciosa'', commonly known as the showy banksia, is a species of large shrub or small tree in the family Proteaceae. It occurs 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. ''Banksia speciosa''. Though widely occurring, it 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, ''Banksia speciosa'' is classified in the series ''Banksia'' within the genus. Its closest relative is ''B. baxteri''. ''Banksia 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, ''Banksia 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''. ==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 long and 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 high and 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 long by wide and 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 long and fairly flattened, and is composed of the seed body proper, measuring long and 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 long and 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 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.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Banksia speciosa」の詳細全文を読む スポンサード リンク
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