Silver Banksia

Appearance

"Banksia marginata" is a highly variable species, usually ranging from a small shrub around a metre tall to a 12-metre-high tree. Unusually large trees of 15 to possibly 30 m have been reported near Beeac in Victoria's Western District as well as several locations in Tasmania, while compact shrubs limited to 20 cm high have been recorded on coastal heathland in Tasmania. Shrubs reach only 2 m high in Gibraltar Range National Park. The bark is pale grey and initially smooth before becoming finely tessellated with age. The new branchlets are hairy at first but lose their hairs as they mature, the new growth a pale or pinkish brown. The leaves are alternately arranged on the stems on 2–5 mm long petioles, and characteristically toothed in juvenile or younger leaves long). The narrow adult leaves are dull green in colour and generally linear, oblong or wedge-shaped and measure 1.5–6 cm long and 0.3–1.3 cm wide. The margins become entire with age, and the tip is most commonly truncate or emarginate, but can be acute or mucronate. The cellular makeup of the leaves shows evidence of lignification, and the leaves themselves are somewhat stiff. Leaves also have sunken stomates. The leaf undersurface is white with a prominent midrib covered in brownish hairs.

The complex flower spikes, known as inflorescences, appear generally from late summer to early winter in New South Wales and Victoria, although flowering occurs in late autumn and winter in the Gibraltar Range. Cylindrical in shape, they are composed of a central woody spike or axis, perpendicularly from which a large number of compact floral units arise, which measure 5–10 cm tall and 4–6 cm wide. Pale yellow in colour, they are composed of up to 1000 individual flowers and arise from nodes on branchlets that are at least three years old. Sometimes two may grow from successive nodes in the same flowering season. They can have a grey or golden tinge in late bud. As with most banksias, anthesis is acropetal; the opening of the individual buds proceeds up the flower spike from the base to the top. Over time the flower spikes fade to brown and then grey, and the old flowers generally persist on the cone. The woody follicles grow in the six months after flowering, with up to 150 developing on a single flower spike. In many populations, only a few follicles develop. Small and elliptic, they measure 0.7–1.7 cm long, 0.2–0.5 cm high, and 0.2–0.4 cm wide. In coastal and floodplain populations, these usually open spontaneously and release seed, while they generally remain sealed until burnt by fire in plants from heathland and montane habitats. Each follicle contains one or two fertile seeds, between which lies a woody dark brown separator of similar shape to the seeds. Measuring 0.9–1.5 cm in length, the seed is egg- to wedge-shaped and composed of a dark brown 0.8–1.1 cm wide membranous "wing" and wedge- or sickle-shaped seed proper which measures 0.5–0.8 cm long by 0.3–0.4 cm wide. The seed surface can be smooth or covered in tiny ridges, and often glistens. The resulting seedling first grows two obovate cotyledon leaves, which may remain for several months as several more leaves appear. The cotyledons of "Banksia marginata", "B. paludosa" and "B. integrifolia" are very similar in appearance.

Naming

"Banksia marginata" is commonly called the silver banksia, because the white undersides of its leaves contrast with the otherwise green foliage and give the plant a "silvery" look. Alternate common names include honeysuckle and dwarf honeysuckle. The aboriginal name in the Jardwadjali language of western Victoria was "warock", while the Kaurna name from the Adelaide Plains was "pitpauwe" and the local name in the Macquarie Harbour region in Tasmania was "tangan".

A widely distributed and diverse plant, "B. marginata" was described independently and given many different names by early explorers. On his third voyage, Captain James Cook reported a "most common tree..about ten feet high, branching pretty much, with narrow leaves, and a large yellow cylindrical flower, consisting only of a vast number of filaments; which, being shed, leave a fruit like a pine top." in January 1777. The species was first collected by Luis Née in 1793, from somewhere between Sydney and Parramatta. In 1800, the Spanish botanist Antonio José Cavanilles gave the species the binomial name it still bears today. The species name is the Latin adjective "marginatus" and refers to appearance of the lower surface of the recurved margins of the leaves when viewed from underneath. Cavanilles also described another specimen collected by Née in the same locality as a different species, "Banksia microstachya" Cav. A smaller shrub with dentate leaves, this turned out to be an immature plant of the same species with juvenile leaves.

Robert Brown described 31 species of "Banksia" in his 1810 work "Prodromus Florae Novae Hollandiae et Insulae Van Diemen", including six taxa now attributable to "B. marginata". He split the genus into two subgenera, placing these species in subgenus "Banksia verae", the "True Banksias". He described "Banksia australis" R.Br., giving the location of the collection as Port Phillip Bay in Victoria in 1802. Brown's other collections which were reduced to synonymy with "B. marginata" were "Banksia depressa" R.Br., a prostrate shrub from Margate Rivulet in southeastern Tasmania, "Banksia insularis" R.Br., from Flinders and King Island, and "Banksia patula" R.Br., a shrub from the vicinity of Port Lincoln, South Australia. The French naturalist Aimé Bonpland in 1816 called it "Banksia marcescens" Bonpl., deemed an "illegitimate name", as by that time the name "Banksia marginata" already had been published. Still more synonyms are "Banksia ferrea" Vent. ex Spreng. and "Banksia gunnii" Meisn.

By the time Carl Meissner published his 1856 arrangement of the genus, there were 58 described "Banksia" species. Meissner divided Brown's "Banksia verae", which had been renamed "Eubanksia" by Stephan Endlicher in 1847, into four series based on leaf properties. He listed six species and a further four varieties all now sunk into "B. marginata" in series "Salicinae".

In 1870, George Bentham published a thorough revision of "Banksia" in his landmark publication "Flora Australiensis". In Bentham's arrangement, the number of recognised "Banksia" species was reduced from 60 to 46. Bentham observed that the characteristics Brown used to define "B. australis", "B. depressa", "B. patula", and "B. insularis" were unable to distinguish separate forms as more specimens came to light, and hence declared them synonyms of "B. marginata". Meissner's four series were replaced by four sections based on leaf, style and pollen-presenter characters. "B. marginata" was placed in section "Eubanksia" along with "B. integrifolia" and "B. dentata".Hybridisation with "Banksia conferta" subsp. "penicillata" at the site of an old abandoned railway between Newnes and Clarence in the Blue Mountains has been recorded; a single "B. marginata" plant was surrounded by plants with intermediate features but more strongly resembling "B. conferta" subsp. "penicillata". "B. marginata" can also interbreed with "B. paludosa" where they are found together. A hybrid with "B. saxicola" was recorded from Mount William during the "Banksia Atlas" project.

A purported hybrid with "B. integrifolia", thought to be from Cape Paterson on Victoria's south coast, was first described by Alf Salkin and is commercially available in small quantities. It forms an attractive hardy low-growing plant to 1 m. Salkin observed an intermediate form which occurred in coastal areas where "Banksia marginata" and "B. integrifolia" are found together. Calling it the "Wilsons Promontory topodeme", he noted that it colonised sand dunes, had leaves similar to but narrower than "integrifolia", and had persisting flowers on old spikes but not as persistent as "marginata". He had collected this form from Revesby in New South Wales as well as Cape Paterson, and had received reports of similar plants at Marlo and Bemm Rivers. Stands of plants intermediate between "B. integrifolia" and "B. marginata" have been recorded near Mallacoota in East Gippsland.

Distribution

"Banksia marginata" is found from Baradine and Gibraltar Range National Park in northern New South Wales, southwards into Victoria and South Australia, as well as across Tasmania. It is found on the major islands of Bass Strait, including King, Flinders and Cape Barren Islands. There is one report of a collection from the Springbrook Mountains southwest of Southport in southeastern Queensland. It is extremely rare in southwestern New South Wales. In Victoria, it is predominantly coastal or near-coastal east of Traralgon, but in New South Wales it is absent from coastal areas in the Sydney region. "Banksia marginata" often grew as a large tree on the basalt plains west of Melbourne, but has almost disappeared. In the vicinity of Adelaide, it was common in the western suburbs on old sand dunes behind the beach foredunes. It remains common in the Adelaide foothills. The annual rainfall over its distribution ranges from 400 to 1,000 mm.

In the Gibraltar Range National Park, it is a dominant shrub of open heathland and a non-dominant shrub of closed heath, mostly found in swampy heath associated with sedges. Plants here have some degree of self-compatibility. In the Sydney region, it grows in association with heath banksia, old man banksia, mountain devil, lance-leaved geebung and dwarf apple in heathland, and with silvertop ash, Blue Mountains ash, Sydney peppermint, scribbly gum, Blue Mountains mallee ash, brittle gum, snow gum and red bloodwood in forested areas.

It is widespread as an understory species in medium rainfall eucalypt forests across Victoria, occurring in association with manna gum, narrow-leaf peppermint, messmate, swamp gum and brown stringybark. It is a common shrub, sometimes small tree, in heathy and shrubby forests as well as coastal scrub and heath in part of its range. In South Gippsland, it is generally a shrub which regenerates from a lignotuber or suckers after bushfire and sets few seed. It has been recorded as a low spreading shrub in Croajingolong National Park in East Gippsland. In the Wombat State Forest west of Melbourne, it grows as a 1 to 2 m high shrub on less fertile soils, and as a large tree to 8 m on more fertile soils. Few trees remain, having been cleared for agriculture or for fuel. Similarly, further west in the Corangamite region, it is either a tree or suckering shrub.

In Tasmania, "Banksia marginata" occupies a wide range of habitats, in mixed forest, button grass moorlands, flood plains of the Loddon, Franklin and Huon Rivers, as well as coastal regions. In parts of the west and southwest of Tasmania, the species is dominant within the threatened native vegetation community known as "Banksia marginata" wet scrub. Interestingly, there is no macrofossil record for the species, so it is unclear whether it is a recent introduction from the mainland or has only recently evolved, although its presence on both the mainland and Tasmania suggests it has been present since the Pleistocene. It grows in coastal habitats that would be occupied by "Banksia integrifolia" on the mainland.

"Banksia marginata" grows on a variety of soil types, from clay loams, shale and peaty loams to sandy or rocky soils composed of quartzite, sandstone, limestone or granite, although sandier soils predominate. It is restricted to sandy soils in the Adelaide region. The soil types are of a wide range of pH, from highly acidic soils in the Grampians to alkaline soils in South Australia. Plants have been recorded at altitudes ranging from sea level to as high as 1,200 m AHD at Mount Field National Park.

Uses

The plant was often used by many indigenous clans and tribes through out the east coast and used in similar fashion as a large amount as others banksia trees.

The sweet nectar fro the flowers was sucked or drained by soaking in water and in some cases mixed with some wattle gum in order to make a sweet lolly

The woods was also used to make needles and the dried flowers were used to strain water for drinking