Banksia Integrifolia "Coastal Banksia" Seeds
“B. integrifolia is a highly variable species. It is most often encountered as a tree up to 25 metres (80 ft) in height, but in sheltered locations it can reach 35 metres (110 ft). In more exposed areas it may grow as a small, gnarled tree, reaching to no more than about 5 metres (15 ft), and in highly exposed positions, such as on exposed coastal headlands, it may even be reduced to a small shrub.
It usually has a single stout trunk, which is often twisted and gnarled, with the rough grey bark characteristic of Banksia. The leaves are dark green with a white underside, and occur in whorls of three to five. Adult leaves have entire margins; George specifies their dimensions as 4 to 20 centimetres (2–8 in) long and 6 to 35 millimetres (0.2–1.4 in) wide, but The Banksia Atlas warns that "Atlas contributors found great variability in these measurements with specimens often falling outside the varietal limits specified by George (1981) or being intermediate between two varieties." Juvenile leaves have dentate margins with a few short teeth, and are generally larger than adult leaves.
Flowers occur in Banksia's characteristic "flower spike", an inflorescence made up of several hundred flowers densely packed in a spiral around a woody axis. This is roughly cylindrical, 10 to 12 centimetres (4–5 in) high and five centimetres (2 in) wide. Flowers are usually pale yellow to yellow, but may be greenish or pinkish in bud. Each individual flower consists of a tubular perianth made up of four united tepals, and one long wiry style. Characteristic of the taxonomic section in which it is placed, the styles are straight rather than hooked. The style ends are initially trapped inside the upper perianth parts, but break free at anthesis. This process starts with the flowers at the bottom of the inflorescence, sweeping up the spike at an unusually high rate of between 96 and 390 flowers per 24 hours.
The flower spikes are not as prominent as in some other Banksia species, as they arise from two- to three-year-old nodes nested within the foliage. After flowering, old flower parts wither and fall away over a period of several months, revealing the "cone", a woody axis embedded with many small follicles. The follicles are initially greenish and downy, but gradually fade to dark grey. Each follicle contains one or sometimes two seeds, separated by a thin wooden separator. The seed itself is black, 6 to 10 millimetres (0.2–0.4 in) long with a feathery black 'wing' 10 to 20 millimetres (0.4–0.8 in) long.
Hardy and versatile, B. integrifolia will grow in clay, sand, acid and even alkaline soils, and it shows good resistance to wind and salt, making it suitable for seaside planting. It is therefore highly regarded as a low-maintenance garden tree, although its large size makes it unsuitable for smaller gardens. Its hardiness may however forewarn weed potential, as some evidence of weediness has been seen in Western Australia and New Zealand. When growing near bushland within its native habitat, it is recommended to obtain local provenance seed or plants if available.
The most common form available in commercial nurseries is unimproved Banksia integrifolia subsp. integrifolia. It prefers a sunny aspect without exposure to frosts, and tolerates fairly heavy pruning. Seeds do not require any treatment, and take 5 to 6 weeks to germinate. Flowering begins at around four to six years from seed. The other subspecies are less well known in cultivation, but are obtainable. Cultivation is presumably similar to B. integrifolia subsp. integrifolia, except that B. integrifolia subsp. monticola may be assumed frost-tolerant. Dwarf forms of B. integrifolia are sometimes sold, and a registered prostrate cultivar, Banksia 'Roller Coaster', is available. The latter is a vigorous ground-hugging plant that can spread to 4 or 5 metres across yet remains only 50 centimetres high.
Because of its high resistance to P. cinnamomi dieback, the feasibility of using B. integrifolia as a rootstock for susceptible Banksia species in the cut flower trade is under investigation. Presently, the success rate for grafting is only 30–40%, and even with successful grafts there is a tendency for the union to fail under stress. More research is needed before the technique will be ready for commercial use.
The wood of B. integrifolia is pink to red, with inconspicuous rings and conspicuous rays. It is spongy and porous, with a density of around 530 kilograms per cubic metre (33 lb/ft3). It is considered highly decorative, but it warps badly on drying, has poor load-bearing qualities, and is susceptible to termite attack; it is therefore unsuitable for most construction purposes. It is sometimes used for cabinet panelling and in ornamental turnery, and natural bends were once sought after for making boat knees. It is a useful firewood.
B. integrifolia produces a dark amber-coloured honey of middling quality and therefore low commercial value. Despite this, the species is highly valued by beekeepers because it produces large amounts of pollen and nectar during autumn and winter, thus helping support hives at a time when little else is flowering.
Historically, indigenous Australians obtained nectar from B. integrifolia by stroking the flower spikes then licking their hands, or by steeping flower spikes in a coolamon overnight. They also used the flower spikes as hairbrushes. Early settlers used the nectar as a syrup for sore throats and colds; and bushmen would impregnate barren "cones" with fat to make a slow-burning candle.
More recently, B. integrifolia has been used in the art of bonsai. Its rangy habit and long internodes are challenging to overcome, but the leaves do reduce with pruning, and unlike the gnarlier B. serrata (saw banksia) its trunk can become textured with age”. Wikipedia 2018
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