Banksia is a genus of wildflowers native to Australia, many of which are also cultivated as garden plants. There are about 170 species, some of which are threatened or endangered by loss of habitat, fire, and the water mold Phytophthora cinnamomi, commonly called dieback. Banksia grows in a variety of Australian climates, though no species grow in the desert. It produces abundant nectar and serves as a food source for bees and other insects, bats, birds, pygmy possums, and rats.
Plants in this genus are either shrubs or trees, the largest species reaching 100 feet (30 meters) in height. Perhaps the most notable feature of Banksia is the flower spike, a woody structure covered with hundreds or thousands of small flowers, which may be red, orange, yellow, pink, or violet. Some species do not have a flower spike, however. B. dentata, or tropical banksia, is the only species that grows outside of Australia, with a range encompassing northern Australia, Papua New Guinea, and the Aru Islands. Over 90 percent of species grow only in southwest Western Australia.
Banksia has adapted to survive bushfires by producing seeds that are stimulated by fire. Though fires kill many of the living plants, they also lead to new growth. Species that do not produce such seeds have either fire-resistant bark or lignotubers, structures that store nutrients and sprout new stems following fire. Despite these adaptations, Banksia is threatened by excessive bushfires that do not allow them time to regrow.
Another threat to the plants, Phytophthora cinnamomi or dieback, attacks the roots, causing them to rot and preventing them from absorbing water and nutrients. Infected plants die within a few years, and the disease is very difficult to treat. The dieback fungus thrives in moist soil, so over watering in gardens often leaves plants vulnerable.
Banksia species are popular as cut flowers and garden plants, though they are sometimes difficult to grow. The largest varieties are popularly planted in parks, streets, and gardens. The plant is also used by beekeepers as a source of abundant nectar, though it does not produce the best honey.
Another important product is the wood, which is used for ornamental purposes and to make small boats. The dried out flower spikes, often called cones, are also used to make decorative products, such as vessels and drink coasters. Australian Aborigines traditionally sucked on the flower spikes for their sweet nectar, or soaked them in water to make a sweet drink.