Firewood banksia

Appearance

"Banksia menziesii" grows either as a gnarled tree to 10 m, or a lower spreading 1–3 metres shrub, generally encountered at its northern limits in the vicinity of Eneabba-Mount Adams; thus, it declines steadily in size as the climate becomes warmer and drier further north. In the shrub form, several stems arise from the woody base known as the lignotuber. The trunk is greyish, sometimes with shades of brown or pink, and the 2–3 cm thick rough bark breaks away easily. The new growth is covered in fine brownish hair, which wears away after two or three years, leaving smooth stems and leaves. Stems that will bear flower spikes the following year are generally thicker and longer. Oblong in shape and somewhat truncate at the tips, the leaves are grey-green in colour, 8–25 cm long and up to 4 cm wide. The new leaves are paler and finely downy. The leaf margins are serrated with many small 1–2 mm long triangular teeth. The lower surface of the leaf has a midrib covered in fine pale brown hair.

Flowering occurs in autumn and winter, peaking from May to July. Overall the inflorescences, or flower spikes, take around eight months to development from the first microscopic changes in late spring. Ovoid to cylindrical in shape, the flower spikes can be up to 7–8 cm wide and 4–12 cm high. They are composed of numerous individual flowers; one field study south of Perth recorded an average of 1043 per flower spike, while another on plants in cultivation in South Australia recorded an average of 720. "B. menziesii" has more flower colour variants than any other "Banksia" species, with flower spikes occurring in a wide range of pinks, as well as chocolate, bronze, yellow and white, and greenish variants. They are particularly striking closeup but can look indistinct from a distance. They are most attractive in late bud, the styles contrasting well to the body of the inflorescence, the whole looking like a red- or pink-and white vertical candy striped bloom. The inflorescences are generally a deeper red after colder weather and further into the winter. Anthocyanin pigments are responsible for the red and pink shades in the flowers.

Old flowers usually fall off the spikes quickly, with up to 25 large beaked follicles developing. A mottled dark brown and grey in colour, these can be prominent and quite attractively patterned when newly developed. Oval shaped, they are 2.5–3.5 cm long by 1–1.5 cm high and 1–1.5 cm wide. Overall, only a small fraction of flowers develop into follicles; the proportion is as low as one in a thousand. The plant is dependent on fire to reproduce as the follicles only open after being burnt, each one producing one or two viable wedge-shaped seeds, on either side of a woody separator. The colour and level of pigmentation in the seeds foreshadows the eventual colour of the inflorescences. Kevin Collins of the Banksia Farm recalled that for many years pale seeds were discarded by seed collectors who thought they were infertile. Later, he learnt that pale seeds yielded yellow-coloured blooms, dark grey the usual red-coloured, and black a distinctive bronze-coloured bloom.

Seedlings have obovate cotyledons 1–1.4 cm long by 1–1.5 cm wide, and the leaves that develop immediately afterward are crowded and very hairy. They have serrate margins. Evidence of thickening to form a future lignotuber, as well as minute buds, has been detected from the bases of seedlings at five months of age.

Naming

The common name of firewood banksia was a result of its quick-burning properties. Other names recorded include Menzies banksia, firewheel banksia, port wine banksia, flame banksia, and in the cut flower industry, strawberry banksia and raspberry frost banksia. The Beeloo Whadjuk Noongar people of the Perth region knew it as the "Mungyt". Despite its variation across its range, George noted that "B. menziesii" was a clearly defined species, and no formal division into subspecies was warranted.

Its Noongar name is Bulgalla.

Distribution

"Banksia menziesii" grows primarily in deep sandy soils of the Swan Coastal Plain and Geraldton Sandplains, extending from Waroona in the south to Kalbarri in the north. However, it is uncommon south of Mandurah. It is generally limited to the east by the heavy soils of the Darling Scarp, but does grow on isolated patches of sand in the Jarrah Forest and Avon Wheatbelt regions, such as occur near Beverley, Toodyay and Wongan Hills. The easternmost known occurrence is a specimen collected by Roger Hnatiuk in 1979 from north-east of Brookton, about 125 km from the coast. Much of its range on the Swan Coastal Plain coincides with Perth's expanding metropolitan area, and much habitat has been lost to clearing.

Evolution

Specimens of "B. menziesii" were first collected by the botanist Charles Fraser during Captain James Stirling's March 1827 exploration of the Swan River. The following year, Alexander Macleay sent some of Fraser's specimens to Robert Brown. Brown formally published the species in his 1830 "Supplementum Primum Prodromi Florae Novae Hollandiae", giving it the specific epithet in honor of Archibald Menzies, surgeon-naturalist on HMS "Discovery" under George Vancouver, who discovered King George Sound in 1791. Thus the species' full name is "Banksia menziesii" R.Br. Neither Brown nor Menzies ever saw the plant growing.

Under Brown's taxonomic arrangement, "B. menziesii" was placed in subgenus "Banksia verae", the "True Banksias", because its inflorescence is a typical "Banksia" flower spike. "Banksia verae" was renamed "Eubanksia" by Stephan Endlicher in 1847, and demoted to sectional rank by Carl Meissner in his 1856 classification. Meissner further divided "Eubanksia" into four series, with "B. menziesii" placed in series "Salicinae". When George Bentham published his 1870 arrangement in "Flora Australiensis", he discarded Meissner's series, replacing them with four sections. "B. menziesii" was placed in "Orthostylis", a somewhat heterogeneous section containing 18 species. This arrangement would stand for over a century.

In 1891, Otto Kuntze, in his "Revisio Generum Plantarum", rejected the generic name "Banksia" L.f., on the grounds that the name "Banksia" had previously been published in 1776 as "Banksia" J.R.Forst & G.Forst, referring to the genus now known as "Pimelea". Kuntze proposed "Sirmuellera" as an alternative, referring to this species as "Sirmuellera menziesii". This application of the principle of priority was largely ignored by Kuntze's contemporaries, and "Banksia" L.f. was formally conserved and "Sirmuellera" rejected in 1940.