Ixerba facts for kids

Quick facts for kids Ixerba
Tawari, Bay of Plenty
Scientific classification
Genus:	Ixerba
Species:	brexioides

The Ixerba brexioides, also known as tawari (or whakou when it's flowering), is a special tree found only in the northern part of New Zealand's North Island. It's the only species in its group, called Ixerba. This bushy tree has thick, dark green leaves with jagged edges. Its beautiful white flowers have a green center and grow in bunches. When the fruit ripens, it's a green pod that opens up to show shiny black seeds. These seeds are partly covered by a bright red, fleshy part, which looks amazing against the white inside of the fruit. The tawari tree belongs to the plant family Strasburgeriaceae.

About the Tawari Tree

Trunk and Leaves

The tawari is a small tree that can grow up to 10 meters (about 33 feet) tall. It has a wide, spreading top, and its trunk is usually dark to grayish-brown. The leaves grow in a special way: they are arranged one after another along the stem, often forming a circle at the end of a growth period.

The leaves are a bit thick and feel like leather. They are yellowish to dark green on top and pale green underneath. They are shaped like a spear or an oval, measuring about 6-16 cm (2.4-6.3 inches) long and 1-4 cm (0.4-1.6 inches) wide. Their edges are rough and jagged, and each little tooth has a tiny gland. Young leaves are often reddish and have edges that curl inwards. Older leaves can turn orange or red before they fall off.

Flowers and Reproduction

Tawari flowers start to form in March and April, then they open from October to December, depending on where the tree is located. The flowers grow in bunches at the ends of the branches, with five to fifteen flowers in each bunch.

Each flower is like a star, about 2.5-3.5 cm (1-1.4 inches) across. They produce a lot of sweet liquid called nectar, but they don't seem to have a smell. Each flower has five soft, oval-shaped green parts called sepals, and five white, spoon-shaped petals. The petals are fuzzy and have a narrow base. The flower also has five long, white stamens (the male parts that hold pollen) that stick out far from the petals. The nectar is made by special parts in the center of the flower.

Fruit and Seeds

The fruit of the tawari is a tough, leathery pod that is broadly oval. When it's ripe, usually by April, it splits open from the bottom into five sections. Inside each section, there are two shiny black seeds. These seeds are shaped like a slightly curved teardrop, about 6 mm (0.24 inches) long. They are partly covered by a bright scarlet red, fleshy part called an aril. This red aril and the black seeds stand out sharply against the hard, white inside of the fruit.

How Tawari is Classified

Over time, scientists have changed their minds about which plant family tawari belongs to. It was once thought to be related to trees like Brexia. However, after looking closely at its genes, scientists found that Ixerba was not very closely related to Brexia after all.

For a while, Ixerba was placed in its own family called Ixerbaceae. But more tests showed that Ixerba is actually very closely related to another plant from New Caledonia called Strasburgeria. Because of this, Ixerba is now placed in the family Strasburgeriaceae.

Family Tree

Scientists have found old fossil pieces of Ixerba from about 15 million years ago.

Here's how scientists think Ixerba is related to other plants:

Name Meaning

The name Ixerba is a jumbled-up version (an anagram) of Brexia. This is because the tawari tree looks a bit like the Brexia tree, which grows in Madagascar and East Africa. The second part of its scientific name, brexioides, means "like Brexia."

Where Tawari Grows

The tawari tree is found only in the North Island of New Zealand. It grows roughly north of the city of Taupo. You can find it in many places, from Kaitaia in the north down to Waitomo and Te Urewera. It also grows in places like the Waitākere Ranges, Waipoua Forest, and on the Coromandel Peninsula. It can even be found at higher elevations on the Barrier Islands and around the Bay of Plenty.

Tawari's Role in Nature

Tawari often grows alongside the New Zealand kauri tree in the lower parts of lowland rainforests. It's also common in cloud forests up to 700 meters (about 2,300 feet) high. This tree likes shady or protected spots, often where the soil is always damp and near streams. While you might find many tawari trees in one area, generally, individual trees are spread out. It's also common in forests that are regrowing after being disturbed.

Tawari flowers produce a lot of nectar, which attracts many different visitors. Each flower makes about 18 microliters of nectar, which is about 20% sugar. Birds are the main pollinators, meaning they help spread the pollen from flower to flower. However, in forests where there aren't many birds, large flies, moths, honey bees, bumblebees, native bees, wasps, and beetles also visit the flowers. The way the flowers are shaped, with their wide-spreading stamens, suggests they are well-suited for bird pollination.

The seed pods develop between January and April. When they open, they show up to ten shiny, purple-black seeds, partly covered by that bright orange, fleshy aril. Birds like the kereru, whitehead, hihi, and kaka are important for spreading these seeds.

Uses of Tawari

Tawari is a great source of nectar, so much so that bees often make honey mostly from tawari flowers. This special tawari honey is often sold in food shops in New Zealand. The nectar has a lot of fructose (a type of sugar) and water, which can make the honey a bit thin, but it still crystallizes quickly. Tawari honey is light in color and tastes a bit like butterscotch. If at least 20% of the pollen in the honey comes from tawari, it can be sold as tawari honey.

The bark of the tawari tree can be used to make a black dye, which was traditionally used on flax. The Māori people also used the beautiful tawari flowers to make necklaces and other decorations for special celebrations.

Growing Tawari

It can be quite tricky to grow tawari trees in gardens. They need a protected spot, soil rich in plant matter (humus), and good drainage. However, the soil should never dry out completely. It's thought that tawari might need a special type of fungus (called a mycorrhiza) to help it grow. Interestingly, if you plant tawari next to a Kapuka tree (Griselinia littoralis), the tawari often grows much better!

External Links

• Photo series illustrating many details of the anatomy