Why is the macadamia shell so hard?
Macadamia is the oil-rich seed of an Australian evergreen tree enclosed by an exceptionally hard shell.
Structure, development and life cycle
The green outer husk separates at maturity, leaving a thick lignin-rich shell. This mechanical layer protects the embryo from impact, drying and some consumers. The edible kernel loses moisture during maturity and drying. Macadamia integrifolia, M. tetraphylla and their hybrids underpin commercial cultivars.
Growing, uses and cautions
A mild subtropical climate with low frost risk, deep draining soil and wind protection is suitable. Some cultivars benefit from cross-pollination, and bees visit the flowers. Shelling requires controlled mechanical force without crushing kernels. Macadamia is toxic to dogs and even small ingestion may require veterinary advice.
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