There are 173 individual species of Banskia, 172 of which are native to Australia. The genus was named in honour of Sir Joseph Banks, the botanist attached to the Endeavour in 1770. Banks was the first European to collect specimens of Banskia. A member of the Proteaceae family, the Banskia is a relative of other well-known genera such as Grevillea, Telopea, Leucodendron, and Macadamia. Australia and South Africa have the greatest concentrations of Proteaceae species. The family is large, and is a good example of Southern Hemisphere floristic geography, due to the fact that the family can be located in every continent in the hemisphere, barring Antarctica.
Protea is unusual as it contains xylose as the main sugar in its nectar (xylose comrises 39% of nectar sugars in Proteas, which is puzzling due to the fact that insect and bird pollinators are averse to the chemical, while mice [another plant pollinator] will drink pure xylose), while sucrose is the main sugar present in Grevillea. Many species in the Proteaceae family accumulate aluminum. Cyanogenic glycosides are also present. These glycosides are stored in the vacuole (the organelle containing inorganic and organic molecules, including enzymes in solution), and are released if the plant is attacked, and are activated by the enzymes in the cytoplasm. The glycosides then remove the sugar part of the molecule and then release hydrogen cyanide. Some plants, including those in the Proteaceae family, use this toxin as a defense against herbivores, as is evidenced in the presence of hydrogen cyanide in the flowers and seedpods of Grevillea bansksii.
In a bush-regeneration setting, Banksia is planted both in the hind-dunes and the plateau zone on Hawkesbury Sandstone. Both environments form sandy soils, which are both nutrient-poor and demonstrate low water holding capacity. Proteiod roots were first described among members of the Proteaceae family growing in the Leipzig Botanic Gardens in 1894, but only acquired the name “Proteiod” in 1960, when Helen Purnell examined 44 species over 10 genera, and discovered the same interesting root morphology in every Proteaceae genus except Persoonia.
Proteiod roots are now known to occur in 27 different Proteaceae genera – in addition: 30 species from other genera are also known to possess Proteiod roots. Similar sub-ground structures have also been observed to occur in the Cyperaceae and Restionaceae families, but botanists have yet to study the physiology of these families. There are two forms of “proteiod roots”: “Simple” cluster roots, forming rootlets along only one root, and “compound” cluster roots, which form primary rootlets, but also form secondary rootlets on the primary rootlets. The Proteaceae family also has a demonstrable symbiosis with the soil-bound water mould Phytophthora cinnamomi. There have been ongoing studies on this symbiotic relationship between mycorrhizal fungi and Proteaceae and non-Proteaceae plants in the Jurien Bay area in Western Australia (for further reading on this, go to: http://riawa.com.au/wordpress/wp-content/uploads/2014/10/2014-LAMBERS_Phosphorus-nutrition-of-phosphorus-sensitive-plants.pdf)
In cultivation, Bansksias (and other natives, including all those in Proteaceae) require fertilisers that are low in phosphorus and high in nitrogen such as Seasol® or Osmocote Native®. Products containing higher levels of phosphorous cause phosphorus toxicity and sometimes iron deficiency among native plants, which are adapted to growing in low levels of phosphorous.
References:
SW, J. (2016). Xylose as a nectar sugar: from biochemistry to ecology. – PubMed – NCBI. [online] Ncbi.nlm.nih.gov. Available at: https://www.ncbi.nlm.nih.gov/pubmed/11923077
[Accessed 11 Oct. 2016].
Wiemeyer SN, e. (2016). Acute oral toxicity of sodium cyanide in birds. – PubMed – NCBI. [online] Ncbi.nlm.nih.gov. Available at: https://www.ncbi.nlm.nih.gov/pubmed/3503141 [Accessed 11 Oct. 2016].