Tropical banksia facts for kids
Quick facts for kids Tropical banksia |
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| Banksia dentata, young follicles. | |
| Scientific classification | |
| Genus: |
Banksia
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| Species: |
dentata
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| Range across northern Australia, southern New Guinea and Aru Islands (Trangan) | |
| Synonyms | |
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The Banksia dentata, often called the tropical banksia, is a type of tree. It grows in northern Australia, southern New Guinea, and the Aru Islands. This tree can reach up to 7 meters (23 feet) tall. It has large green leaves that are up to 22 centimeters (8.7 inches) long. The edges of its leaves are "dentate," meaning they are toothed like a saw.
Its yellow flower spikes are shaped like cylinders. They grow up to 13 centimeters (5.1 inches) tall. These flowers appear during the cooler months. They attract many animals, including different kinds of honeyeater birds and sunbirds. The sugar glider and various insects also visit the flowers. After the flowers fade, the spikes swell. They grow seed pods called follicles. Each follicle can hold up to two seeds.
Banksia dentata was one of the first four Banksia species ever found. Sir Joseph Banks collected it in 1770. It was officially described in 1782 by Carolus Linnaeus the Younger. This plant is found in tropical grasslands called savannas. It often grows near Pandanus and Melaleuca trees. After a bushfire, it can regrow from its woody base. This special base is called a lignotuber.
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What the Tropical Banksia Looks Like
The tropical banksia is usually a small tree. It often grows to about 4 meters (13 feet) tall. Sometimes, it can reach 7 meters (23 feet). It has a thick, rough trunk and branches that spread out. The bark is dark grey and looks like a pattern of tiles.
Young branches are covered in reddish hair. As they get older, they become smooth and grey. The large green leaves are spread along the stems. They are more crowded at the ends of the branches. Each leaf is 9 to 22 centimeters (3.5 to 8.7 inches) long. They are 2 to 9 centimeters (0.8 to 3.5 inches) wide. Their shape is wider at the tip and narrower at the base. The tips are pointed.
The edges of the leaves are toothed. The teeth are 0.1 to 1.3 centimeters (0.04 to 0.5 inches) long. They are separated by U-shaped dips. The leaves are also wavy. Their undersides are white. The main vein of the leaf is raised underneath and sunken on top.
Flower Spikes and Seeds
The yellow flower spikes are cylindrical. They grow on branches that are one to three years old. These spikes appear between November and May. They are 10 to 13 centimeters (3.9 to 5.1 inches) tall. They are 5 to 10 centimeters (2 to 3.9 inches) wide. When new, the flower spikes smell like corn. All parts of the flower are pale yellow.
After the flowers open, their parts soon fall off. The spikes then turn into irregular, cylinder-shaped fruit clusters. The oval seed pods, or follicles, are 1.5 to 2 centimeters (0.6 to 0.8 inches) long. They are 0.4 to 0.8 centimeters (0.16 to 0.31 inches) high and wide. When young, they are pale green and furry. As they get older, they become smooth and pale brown. The follicles open by themselves when they are ready.
Each follicle holds two seeds. Between the seeds is a woody, dark brown separator. This separator is shaped like the seeds. The seeds are 1.8 to 2.1 centimeters (0.7 to 0.8 inches) long. They are wider at the tip and narrower at the base. Each seed has a dark brown, thin "wing." This wing is 1.1 to 1.4 centimeters (0.4 to 0.6 inches) wide. The main part of the seed is 1.0 to 1.2 centimeters (0.4 to 0.5 inches) long. It is 0.5 to 0.8 centimeters (0.2 to 0.3 inches) wide. The surface of the seed can be smooth or have tiny ridges.
How Seedlings Grow
The first leaves of a seedling are called cotyledons. They are bright green and oval-shaped. They measure 1.6 to 1.9 centimeters (0.6 to 0.7 inches) long. They are 0.8 to 1.1 centimeters (0.3 to 0.4 inches) wide. At the base of each cotyledon are two small, pointed parts.
The stem of the seedling is 3 to 4 millimeters (0.12 to 0.16 inches) tall. The next leaves grow in pairs, opposite each other. They are roughly linear in shape. They measure 2.5 to 2.7 centimeters (1.0 to 1.1 inches) long. They are 0.4 to 0.5 centimeters (0.16 to 0.20 inches) wide. These leaves have two to three small "teeth" on their upper part. The underside of these leaves is covered with white hair. As the plant grows, later leaves become more oval-shaped. They are 3 to 7 centimeters (1.2 to 2.8 inches) long. They are 0.8 to 1.2 centimeters (0.3 to 0.5 inches) wide. These leaves also have toothed edges and pointed tips. The stems of young seedlings are hairy.
Naming the Tropical Banksia
Scientists Joseph Banks and Daniel Solander collected samples of Banksia dentata. This happened between June and August 1770. They were on the Endeavour with Captain James Cook. However, the description of the species was not published until 1782. This is when Carolus Linnaeus the Younger described the first four Banksia species. He named them based on their leaf shapes. So, this species was named dentata because its leaves have "toothed" edges. Dentata is the Latin word for "toothed."
This species is unique, meaning it has no known subspecies. Even though it has not been studied closely, reports suggest it does not change much across its wide range.
Over time, other botanists tried to rename Banksia dentata. For example, Otto Kuntze tried to change its name to Sirmuellera dentata in 1891. James Britten tried to rename it Isostylis dentata in 1905. But these changes did not stick. In 1940, the name Banksia was officially protected.
The tropical banksia has other local names. In Kakadu National Park, it is called guibuk. In the Nunggubuyu language of eastern Arnhem Land, it is rilirdili. People on Groote Eylandt call it Enindurrkwa. In Yirrkala, it is known as gulpu.
Where it Fits in the Banksia Family
Today, the way Banksia plants are grouped is based on botanist Alex George's work from 1999. In this system, Banksia dentata is part of the Banksia subgenus. This is because its flowers grow in the typical Banksia spikes. It is also in the Banksia section because its styles (a part of the flower) are straight. Finally, it is in the Salicinae series because its flower spikes are cylindrical.
Scientists have debated which other Banksia species are its closest relatives. Some studies suggest it is an early branch in the Salicinae group. This means it might be one of the older types of banksias.
Here is a simplified look at where B. dentata fits in the Banksia family:
*'''B. dentata – B. aquilonia – B. integrifolia – B. plagiocarpa – B. oblongifolia – B. robur – B. conferta – B. paludosa – B. marginata – B. canei – B. saxicola
Where the Tropical Banksia Grows
Banksia dentata is found across northern Australia. It grows as far west as the Wunaamin Miliwundi Ranges in the Kimberley region. It extends through the Northern Territory and south to Katherine Gorge. In Queensland, it grows on the Cape York Peninsula down to Cooktown. It is also found on islands like Groote Eylandt, the Wessel Islands, Melville, and Bathurst Island.
This banksia also grows in the Aru Islands and New Guinea. In New Guinea, it ranges from Merauke east to Port Moresby. It is also found around Bulolo and Mount Mau. Banksia dentata is the only Banksia species not found only in Australia. Because much of its habitat is remote, it might grow in even more places than we know.
Habitat and Environment
Banksia dentata usually grows in sandy soils. It is found in savanna woodlands or shrublands. These areas are often near freshwater swamps, rivers, or floodplains. These places are wet during certain seasons. It can also grow on rocky areas made of quartzite or sandstone. In Australia, it grows up to about 500 meters (1,600 feet) high. In New Guinea, it can be found up to 1,200 meters (3,900 feet) high. In New Guinea, it only grows in areas with a clear dry season.
Banksia dentata often grows with Melaleuca and Pandanus species. On Cape York, it is a main plant in a low scrub area. This area is called "wet desert" because it looks dry but is in a monsoon climate. On soils with little phosphorus, it grows with Melaleuca saligna. On Melville Island, it is a main part of low banksia woodlands. Here, it forms a canopy 3 to 6 meters (10 to 20 feet) high. It grows with Melaleuca viridiflora.
How the Tropical Banksia Lives
Banksia dentata can survive bushfires. It does this by regrowing from its woody base, called a lignotuber. Unlike some other banksias, it does not have hidden buds at its base. The areas where it grows often have fires. If fires happen often, this banksia can become more common.
One special feature of its leaves helps it live in sunny, dry places. It has a thick layer under the outer skin of the leaf. This layer has large spaces filled with a special compound. This compound helps reduce how much sunlight reaches the inner parts of the leaf.
Animals and Pollination
Many insects that feed on nectar are drawn to the flower spikes. These insects then attract birds like honeyeaters, silvereyes, and sunbirds. Many of these birds eat both nectar and insects. The sugar glider (a small marsupial) also feeds on the flower spikes. It likely helps pollinate the plant. The common blossom bat also drinks nectar from the flowers.
Banksia dentata is a host plant for certain mistletoe species. These include Amyema benthamii and Decaisnina angustata.
Growing and Using the Tropical Banksia
The tropical banksia is a beautiful plant for gardens. Its rough bark, large green leaves, and yellow flower spikes are attractive. In colder places, like Melbourne, it can struggle in winter. But it usually recovers in the hotter summer months. It cannot be grown in very cold climates, like Canberra.
Plants grown from seed usually start flowering after 5 to 8 years. You can prune the plants hard. They grow best in sandy, slightly acidic soil. The soil should have a pH of 5.5–6.5. These trees can be attacked by borers. The seeds do not need any special treatment to grow. They usually sprout in 32 to 40 days. Banksia dentata was first brought to the United Kingdom in 1822.
Traditional Uses
Banksia dentata is a source of nectar for honey bees. Aboriginal people in the Northern Territory used old seed cones as firebrands. These would burn for up to two hours. Indigenous people also drank the nectar. A hot, smoking flower spike was used to treat leprosy sores. People with diarrhea would squat over smoking cones, hoping it would help them. The thin, woody spikes that did not grow seed pods were used as nose ornaments by Aboriginal women. Flower spikes were also used as combs.
Images for kids
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developing follicles
