| General Description | The size of the crown can reach a length of up to 13 m. The crown is always covered by many branches full of leaves making it look as a perfect shade tree, but there are some considerations to think about first; due to the fact that it has a superficial root system that makes it susceptible to falling during storms. However, it still can be used for shade, but crown cleaning is necessary in order to reduce wind retention. |
| ID Characteristic | Short cylindrical trunk whitish grey coloured, free of branches in the first meter height and the fully circulated for diagonal to horizontal branches that develop 4 leaves per whorl. Forming a rounded upright shape with a dark green foliage colour with elongated pointy serrated leaves with an oblong shape with a pointy end 7-25 cm. large by 3 cm. wide. |
| Shape | Macadamia tetraphylla is a round upright shape tree, but in between of the different cultivars shapes can differ as well, for example; Macai Cultivar spreads on umbrella shape and kau cultivar spreads on broad-upright shape cultivar. Macadamia Nut tree has a central trunk till the first meter high, and then start to develop several branches spreading a canopy between 8 to 13 m. |
| Landscape | Macadamia Nut tree is a good alternative for reforesting deprived areas and restore biodiversity. Not to mention the several extra benefits, such as: avoid landslides, floods, and drought. Macadamia Nut tree has a high economic value due to the richly and flavored nuts that had been used for several purposes, such as: Source of food, oil extraction for cosmetic business, health benefits etc. |
| Propagation | Macadamia tetraphylla tree propagation could be sexual and asexual. Sexual propagation by seed require about 30 to 90 days before germination, the problem with this kind of propagation is that it takes between 8 to 12 years to start to produce fruits, that is why the asexual propagation has become very popular for Macadamia Nut tree propagation.
The most common method of asexual propagation is by grafting being the most used simple whip grafting and side grafting, but the whip grafting has presented better results because less material is necessary and the plants thrives more upright. The propagation has to be done when temperatures are between 15 to 20 °C in order to be able to succeed (spring or autumn). Air-layering is another asexual method that has been used besides cutting-grown but it takes some time to develop root system that’s why grafting is the most used. Plants need to be transplanted to a well drained soil with distances between 4 to 8 m. within rows and 7 to 11 m. between rows. Plants will start to produce fruits between 4 to 5 years after being transplanted and the grafted trees produce between 3 to 4 times more than sexual propagated ones.
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| Cultivation | Macadamia tetraphylla was discovered in Queensland, Australia which is a place that has an average elevation of 111 masl. However, Macadamia Nuts trees grow at altitudes between the sea level to 2000 masl. But in order to thrive and for production purposes altitudes between 700 and 1500 had given better results. Prefer well-drained soils that became from volcanic material (andisols) The ideal pH for Macadamia is between 5.0 to 6.5 It has annual precipitation requirements between 1500 to 3000 mm. Macadamia thrives with temperatures around +15 to +25 °C although with temperatures around +3 °C will be able to survive, and with temperatures above +32 °C the tree suffers from flower abortion. |
| Pests | There are some pest and disease that had been registered as problematic for Macadamia Nut trees some of them are: Fungal diseases: The incidence of fungal diseases is because macadamia nut tree thrives in rainforest environment and also because of the pretty bushy foliage. Pruning is necessary to help with air circulation. The most common funguses are; Anthracnose (Colletotrichum gloeosporides), Husk Spot (Pseudocercospora macadamiae), Raceme Blight (Botrytis cinerea). Pests problems: there are only two very significant; Macadamia Nut Borer (Cryptophlebia ombrodelta), Tropical Nut Borer (Hypothenemus obscurus) Both of them have natural enemies, such as native parasitic wasps and flies. One of them is the wasp Trichgrammatoidea Cryptophlebiae that parasites the larvae Nut Borer. |
| Notable Specimens | Brisbane Botanic Garden, Queensland, Australia. |
| Habitat | It is a native tree from the north east cost of Australia, specifically from Queensland, Australia. Which has an average altitude of 111 meter above sea level. it thrives perfectly with annual precipitations around 1500 to 3000 mm. In terms of soil, it prefers well-drained soils form volcanic origin (Andosol) and pH between 5.0 to 5.6 Macadamia tetraphylla grows directly from the seed and takes between 8 to 12 years to start to produce new fruits. |
| Bark/Stem Description | Short size cylindrical trunk with a smoothie whitish grey bark. The main stem only rises usually till the first meter height and then it spreads several diagonal to horizontal branches. The main stem can reach between 0.20 to 0.70 m. diameter. the secondary branches can reach between 10 to 30 cm. diameter. The tree usually does not change in shape to much comparing the tree when young vs. adult. |
| Flower/Leaf Bud Description | Flowers grow in long racemes about 20 to 30 cm. long, each flower is between 5 to 10 mm. The leaf is oblong with pointy serrated margins. Leaves measure between 7 to 25 cm. the leaf bud is tiny (2 mm.) round shaped with a small pointy side. |
| Leaf Description | Whorled leaves arrangement formed by 4 leaves that are sessile (directly attached to branches, no petiole) with a dark green elongated pointy serrated margin leaf when adult and reddish colour when young, with an oblong shape with a pointy end 7-25 cm. large by 3 cm. and a pinnate leaf venation. |
| Flower Description | The flowers grow in between the leaves whorls in long pendulous inflorescences or racemes 20 to 30 cm. long and each stalk holds between 100 to 300 hermaphrodite cream to pinkish colour. The Macadamia Nut flowers had been catalogued as apetaous flowers or petaloid flowers meaning that they don’t have petals. The flowers are 5 to 15 mm. long. |
| Fruit Description | Macadamia tetraphylla is also know as the Rough-Shelled Macadamia because of his fruit features. M. tetraphylla is drupe fruit that has a round shape between 2 to 3.5 cm. diameter with a pointy end. The fruit is covered by shiny husk that contains one seed that is protected by a woody endocarp that has been described as the harder of all nuts. With a non-smoothie rough appearance. |