Macadamia

The macadamia grows on tall trees.

These trees come from Australia.

They have pretty flowers. The flowers can be pink or purple. The nuts have a very hard shell.

It is hard to crack them open. Large parrots can crack the shells too. These nuts are a tasty snack for people. They are very expensive to buy.

Macadamia trees grow tall and stay green all year.

These trees come from Australia. They are the only food plants native to that land.

The trees grow pretty flowers. These flowers can be white, pink, or purple.

The fruit is a nut with a very tough shell. This shell is much harder than a hazelnut shell. In fact, it is as strong as aluminum.

Because they are so hard, you need a special tool to crack them. Most people use a nutcracker that hits a tiny white dot on the shell.

Macadamias are a very expensive snack. This is because they take a long time to harvest. Some trees take seven to ten years to make many nuts. But once they start, they can grow for over 100 years!

South Africa is now the world's largest producer of these nuts. They grow them in large amounts every year.

The macadamia is a special kind of tree that grows tall and stays green all year.

These trees are part of a group called Proteaceae. They are native to Australia, specifically in parts of Queensland and New South Wales.

For the Aboriginal peoples of Australia, these trees were an important source of bushfood. Today, the macadamia is the only food plant that is native to Australia.

It is a very important plant for people all over the world.

Growing a macadamia nut is a slow and steady process. The tree produces flowers that can be white, pink, or purple.

These flowers grow in long, slender clusters. After the flowers, the tree grows a fruit that is a hard, woody shell. This shell is incredibly tough and holds one or two seeds inside.

It is actually five times harder than a hazelnut shell. It even has strength similar to aluminum. Because it is so hard, you need a special tool to crack it open.

People have been growing these trees for a long time. A botanist named Ferdinand von Mueller named the genus in 1857. He named it to honor a man named John Macadam.

In the 1880s, seeds were sent to Hawaii. For over a hundred years, Hawaii was the biggest producer of these nuts. However, things changed in the 2010s. Now, South Africa is the world's largest producer of macadamias. In 2024, South Africa produced 87,000 tonnes of the nuts.

There are many interesting facts about how these trees live. A tree might not produce many seeds until it is 7 to 10 years old. Once the tree is strong, it can produce nuts for over 100 years. They like fertile soil and plenty of rain. Some varieties, like 'Beaumont', are very popular in gardens. Other types, like 'Nelmac II', have sweet seeds that people like to eat. Scientists found that most Hawaiian trees came from just one small group of trees in Australia. This means they are all very similar to each other.

Even though they are delicious, you must be careful with them. Macadamia nuts are very high in fat and energy.

They can be expensive because they are hard to harvest. You should also know that they are not safe for all animals. Macadamias are toxic to dogs and cats. If a dog eats them, they might feel weak or unable to stand. Humans can also have allergies to these nuts. It is always best to check labels before eating them.

The macadamia is a genus of evergreen trees belonging to the flowering plant family Proteaceae. These trees are indigenous to Australia, specifically found in northeastern New South Wales and parts of central and southeastern Queensland.

While several species exist, two are commercially important for their fruit, known as the macadamia nut. This plant holds a unique place in history as the only widely grown food plant that is native to Australia. For the Aboriginal peoples of Australia, the macadamia was an essential source of bushfood long before global trade began.

To understand how a macadamia grows, one must look at its complex physical structure. The trees grow tall and maintain green leaves throughout the year. These leaves are arranged in whorls of three to six and can be long, broad, or even have spiny edges.

The tree produces flowers in long, slender clusters called racemes. These flowers can appear in shades of white, pink, or purple. Once pollinated, the tree develops a fruit that is a hard, woody, globose follicle. This follicle has a pointed tip and contains one or two seeds inside.

The most famous part of the macadamia is its incredibly tough nutshell, often called the coat. This shell is five times harder than a hazelnut shell and possesses mechanical properties similar to aluminum. It has a Vickers hardness of 35. Because the shell is so strong, it requires approximately 2000 N of force to crack it open.

Most ordinary nutcrackers cannot succeed. Instead, people use specialist tools that apply force to the micropyle, which is a small white dot on the shell. In large commercial operations, rotating steel rollers are used to deshell the nuts.

There are four main species within the macadamia genus. These include *Macadamia integrifolia*, *Macadamia jansenii*, *Macadamia ternifolia*, and *Macadamia tetraphylla*.

Scientists distinguish them by their genetics and physical shapes. While all are part of the genus, only *M. integrifolia* and *M. tetraphylla* are cultivated for human consumption. The other two species, *M. jansenii* and *M. ternifolia*, contain cyanogenic glycosides, which are natural toxins. Some plants previously thought to be macadamias were moved to other genera, such as *Lasjia* or *Virotia*, following genetic studies in 2008.

The history of the macadamia is a story of global movement. The genus was named in 1857 by the German-Australian botanist Ferdinand von Mueller. He named it to honor John Macadam, a Scottish-Australian chemist and politician. In the 1880s, Australian seeds were introduced to Hawaii, where they were planted by William H. Purvis. For over a century, Hawaii was the world's largest producer. However, the leadership changed in the 2010s. South Africa has been the world's largest producer since that time. In 2024, South Africa produced 87,000 tonnes of macadamias, a significant increase from its 54,000-tonne production in 2018.

Cultivating these trees requires patience and specific conditions. Macadamias prefer fertile, well-drained soils and significant rainfall. They grow best in temperatures that do not fall below 0°C, though established trees can survive light frosts. A tree usually does not produce commercial quantities of seeds until it is 7 to 10 years old. However, once a tree is established, it can continue bearing fruit for over 100 years. There are different varieties used by farmers. The 'Beaumont' cultivar is a hybrid that produces crops quickly, often by its fourth year. The 'Nelmac II' cultivar is popular because it has a high ratio of nut meat to shell weight.

Despite their popularity, macadamias present certain risks. The nuts are highly nutritious, containing 76% fat and 14% carbohydrates. Because they are so energy-dense, they are also the most expensive nut in the world.

There are biological risks as well. Macadamias are toxic to both dogs and cats. In dogs, ingestion can lead to weakness, muscle tremors, and hind limb paralysis within 12 hours. For humans, macadamia allergy is a real concern. While it affects less than 5% of people with tree nut allergies in the United States, it can cause reactions ranging from skin irritation to anaphylaxis. Researchers note that because many Hawaiian trees descend from a very small number of Australian trees, the crop lacks genetic diversity, making it vulnerable to diseases.