The Macadamia , m. integrifolia or m. tetraphylla is a nut bearing tree, a genus of eight species in the Proteaceae family, with a distribution to eastern Australia; seven native species and Indonesia; one species. Two of the eight macadamia species, M. integrifolia and M. tetraphylla, produce nuts that are a valuable food crop and of a commercial importance. The rest of the genus possesses poisonous and/or inedible nuts.

Macadamias are small to large spreading evergreen nut trees growing from 6-40 m tall. The tree has ovate or elliptical in shape leaves, 6-30 cm long and 2-13 cm broad, with spiny-prickly edges and beautiful foliage color change of yellow-green-red-pink. The flowers are 5-30 cm long, (individual flowers 10-15 mm), white, pink or purple in color and with four petals. Bees are the major agent in pollination but wind may play some role.

Macadamia Tree – Macadamia Nuts and Uses

Macadamia nuts are round, very hard woody with a pointed apex, containing one or two seeds. When mature, (20-25 years), individual trees can produce 50kg of nuts that have delicious flavor and crunchy texture if they are properly collected and dried out as they fall. Macadamia nuts are counted by many to be the prime edible nut.

Macadamia nuts are rich in oil, 65% to 75% and prized for its high content, close to 22% of the Omega-7 palmitoleic acid. This high content in palmitoleic acid plus macadamia’s high oxidative stability makes it extremely suitable in cosmetics, especially skin care products.

Macadamia Nut Tree Propagation Methods

Macadamia trees are commonly propagated by grafting and do not produce commercial amounts of nuts until they are 7-10 years old, but once established can produce nuts for over 100 years. M.tetraphylla species can be readily propagated from large fresh seed, directly from the tree, placed with the white spot facing down in warm, dampen sand.

Additionally mature tip cuttings of 3-4 leaf nodes or 10 cm long can be rooted in damp warm sand. They will develop a tap-rooting system and if allowed long enough in the sand will produce grape-sized feeding tubercles consisting of  thousands of small radial roots in a clump.

Macadamia nut trees are very tolerant to different types of soil but favor a fertile, well-drained soil and a rainfall of 1,000-2,000 mm, and temperatures above 10°C, (optimum temperature 25°C). They are ideally suited to a frost-free, mild climate with a good deal of rainfall distributed throughout the year. However, once established and toughened they can withstand moderate frosts.

Macadamia trees are very challenging to train in order to give them branch angles. You should retain its trunk to one single trunk until the tree founds its basic scaffold, around 2 meters tall. If you do not maintain one trunk, you will have a multiple-trunked tree close to the ground. Most significantly a central leader is the trees best support against wind.

However, the tree should be thinned out in the center for better light entrance, but too much inner thinning exposes the tree to sunburn. Sunburn causes much set-back of growth and productiveness. Generally speaking, it is of value to perform regular pruning of some inner limbs throughout the tree, especially those which hang down for better light and air ventilation.

Macadamia nuts are toxic to dogs. Ingestion may result in weakness with the inability to stand within 12 hours of ingestion. Recuperation is usually within 48 hours. In Australia there are a host of pests and diseases that trouble macadamias.

macadamia nut tree

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