Banksias - grand and beautiful old Australians

(My apologies for this late posting; I was only just getting into it yesterday afternoon when I received a phone call to tell me that one of the first White-winged Black Terns ever reported in the ACT had appeared on Lake Burley Griffin in the city. The only other time I know of it happening I was in South America! That was the end of my afternoon's writing - but what could I do?!)

When Captain James Cook in the Endeavour stopped at the site where the south Sydney suburb of Kurnell now stands in late April 1770 his initial reaction was to call the bay Sting Ray Harbour, but after the remarkable collecting spree of Joseph Banks and Daniel Solander he amended it to Botanists Bay, then almost immediately to Botany Bay.

Among the collections made on that rich visit was a sample of the first banksia to be described by science; 12 years later it was named in Banks' honour by Linnaeus the Younger, son of the famous Carl. This first banksia to be named, the type species, was the grand Saw Banksia B. serrata (both names refer to the toothed leaves), which can grow to a 15 metre high gnarled tree in coastal forests from southern Queensland to Victoria.

Banksia serrata, south coast New South Wales, above and below.

 

Banksias are members of the old Gondwanan family Proteaceae, which I talked about here recently. As I also mentioned in that posting, a 2007 publication, which has been widely accepted, subsumed the large genus Dryandra into Banksia, but that acceptance is not universal. Given that one who vehemently and cogently opposes it is the acknowledged bankia expert, Western Australian Alex George, I am inclined to take a cautious approach. For the purposes of this posting I am limiting to myself to the traditional understanding of banksia - that still leaves us with 78 species to admire however.

Banksias arose in Australia and, with one minor exception, have never left it. Banksia-like trees are known from the fossil record up to 70 million years ago and fossils of 'modern' banksias date back nearly 50 million years.

As is often the case, the south-western corner of the continent has by far the largest number of species, with less than 20 in the south-east and only six in the tropics, of which only three are solely tropical. One of these, the Tropical Banksia B. dentata, is the only species to have left Australia - as well as growing across northern Australia it extends into New Guinea.

Tropical Banksia, Litchfield NP, south-west of Darwin.

The banksia flower spike ('inflorescence' if you're feeling pedantic) is one of its most distinctive features and banksia flowers are among the most widely recognised Australian wildflowers. The woody stem of the inflorescence is covered with densely packed flowers - each single one, unsurprisingly, resembles a grevillea flower - of which there may be hundreds or even thousands. The opening of the flowers from the bottom up (or vice versa in a few cases) produces an impressive slow-motion wave of colour over a period of days. In bud the long style is trapped in the short corolla of petals.

Hooker's Banksia B. hookeriana, Lake Logue NR, north of Perth.
This species is restricted to a small area near Enneaba.

Firewood Banksia B. menziesii Badgingarra NP, north of Perth.
Another inhabitant of the northern sandplains but more widely distributed, from east of Perth to the Murchison River.

Showy Banksia B. speciosa, Cape Le Grande NP, south-east Western Australia.
This one is limited to the south-east sandplains.

After the flowers dry, they may either adhere to the woody stem or drop off entirely.

Persistent dead flowers, Silver Banksia B. marginata, Canberra.

 Only a few of the numerous flowers are likely to be fertilised.

Showy Banksia 'cones', Esperance, south-east Western Australia.
Each fruit contains only one or two small seeds. Many heathland species require a fire's heat
to open the fruit and release the seeds. The cone on the right appears to have no fertilised flowers.

Banksia cone (species uncertain), having dropped seeds post-fire, Fitzgerald River NP,
central southern Western Australia.

Silver Banksia cone with a relatively high rate of fertilisation - the seeds have dropped.
This species lives in forest situations and doesn't require a fires heat to trigger seed drop.

Many species have yellow flowers but there is a range of unexpected colours as well.

Scarlet Banksia B. coccinea Esperance.
The styles still caught in the floral tube, and those released, are very visible here.

Cut-leaf Banksia B. praemorsa, Torndirrup NP near Albany, southern Western Australia.
This truly beautiful species grows only in a tiny area near Albany, very close to the sea,
often among granite boulders.

Heath-leaved Banksia B. ericifolia Nowra.
Here the contrast between styles and floral tubes is spectacular.

Many species favour heathy situations, especially on sand.

Massed Firewood and Hooker's Banksias, Lake Logue NR, north of Perth.
Such scenes are fairly typical of the sandplains, although the extent of this banksia mass is still exceptional.

Others are more specialised - Granite Banksia B. verticillata for instance grows only on or alongside granite outcrops, and only around Walpole and Albany on the Western Australian south coast.

Granite Banksia, Torndirrup NP.

While most banksia inflorescences are large - a Cutleaf Banksia flower spike for instance, while not the largest, can be 27cm long and 6cm wide - some are relatively minute.

The pretty little Teasel Banksia B. pulchella flower, from the central south coast of WA,
is only 5cm in diameter. (North of Esperance.)

Flower appearance is of course driven by pollinators and most banksias seem to be bird-attractors - the numerous flowers of a single spike offer a big reward. 

Little Wattlebird Anthochaera chrysoptera on Saw Banksia, south coast New South Wales.

Western Wattlebird Anthochaera lunulata on Showy Banksia, Esperance.

However recent work has demonstrated the unsuspected significance of mammals in banksia pollination. On the south coast of New South Wales experiments involving putting bags over Hairpin Banksia flowers either by day or night showed that flowers pollinated only by mammals (ie at night) had three times the seed set of those accessible only to birds and insects (by day). The most important pollinators were Brown Antechinus Antechinus stuartii (supposedly carnivorous),  Sugar Gliders Petaurus breviceps, Eastern Pygmy Possums Cercartetus nanus and Bush Rats Rattus fuscipes, another surprise.

Sugar Glides (above) and Bush Rat (below),
important Banksia pollinators.

Hairpin Banksia B. spinulosa Kanangra Boyd NP.
The styles are very stiff, and apparently act as combs to remove pollen from fur.

And once we start to look there are quite a few banksias which are fairly clearly evolved to mammal pollinators, which also means hiding from birds. The flowers tend to be brown and hidden within foliage  - moreover some of them are reported to have a musky 'mouse-like' scent.

Desert Banksia B. ornata, Cox's Scrub Conservation Park, south of Adelaide, South Australia.
The 'desert' here is actually a botanically rich area of heathland and mallee shrubland on sand in
South Australia and western Victoria - the term is a local one referring to low soil nutrients,
hence its unsuitability for farming.

Fox Banksia B. sphaerocarpa, Badgingarra NR, north of Perth.

Some Western Australian species have flowers sitting right on the ground, from stems on or just below the surface, to be even more convenient for furry visitors.

Creeping Banksia B. repens, Stirling Ranges NP, southern Western Australia.

Not all banksia-animal interactions are beneficial to the plant of course; the seemingly rock-hard 'cones' are impervious to most jaws, but the magnificent big black-cockatoos specialise in crushing them open to extract the seeds.

Yellow-tailed Black-Cockatoo Calyptorhynchus funereus extracting seed from
Coastal Banksia B. integrifolia cone.

Carnaby's (Short-billed) Black-Cockatoos Calyptorhynchus latirostris seeking
seeds from Slender Banksia B. attenuata, just north of Perth.

For me, banksias are almost up there with orchids as my favourite wildflowers (or that is to say, they would be if I had favourites...). The fact that they are genuine Old Australians only increases my affection for them.

Acorn Banksia B. prionotes,  Moore River NP, north of Perth.

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