Tuateawa Weed Spot: Coastal Banksia

Joseph Banks, who sailed with Captain Cook, gave his name to the group of Australian shrubs and trees that we know as Banksias. Studies since 2000 suggest that the coastal banksia, Banksia integrifolia, is in the top five newly identified weed species. These images are of a solitary plant in the dune system at Waikawau Bay. You can see that it is full of flower and appears close to seeding. The seeds germinate in 5 to 6 weeks. The species is found along much of the eastern coast of Australia and ranges up into the mountains. It is frequently used in it's home country to stabilise dunes. It has a preference for sandy soils and good drainage and is averse to clay soils.

A visit to Little Bay gives a clue as to where the Waikawau Bay plant might have originated. Coastal Banksias have existed there for many years. They are now undergoing an explosion of numbers. They grow in the clay cliffs but, also, in the rock crevices where pohutakawa often start their lives. There are many small plants growing on the cliff face and a good quantity of considerable size. In a short time they will a major component of the vegetation. It is to be hoped that the pohutakawas will be able to coexist. It is also to be hoped that the large trees will not destabilise the cliff face. A fair sized recent slip did include a number of banksias but this could have been coincidental rather than causative.

Of more concern is the presence of this species in the dunes at Waikawau Bay. The single plant found was very robust and much larger than the pohutakawa planted there over the last twenty or so years. Given its dune stabilising ability this species could markedly change the Waikawau environment in a fairly short time.