Like many other trees from Australia, the macadamia thrives in Hawaii. Others suited to the Islands are many grevillea, melaleuca, callistemon and eucalyptus species. When it comes to our favorite nut, many folks on the mainland think of macadamia nut trees are native to Hawaii, but here we know it is an Australian tree that we adopted as our own.
University of Hawaii scientists took the wild forms and developed the many improved varieties we have today. We use the nut in all kinds of local dishes, especially desserts. We even use the leaves for holiday decorations instead of holly.
When the first humans arrived in Hawaii, edible nutritional kernels or nuts were hard to find. About the only native nut was the mahoe, or Alectron macrococculus. Polynesian then brought with them the coconut and the kukui nut. Technically, the coconut is not a true nut. Although kukui nut is edible, it can create serious stomach issues when too many are eaten since it is related to the castor bean. So in the arena of foods and nutrition, true nuts were lacking.
In the 20th century, University of Hawaii College of Tropical Agriculture researchers literally scoured the tropical world for nut crops that might adapt to some of Hawaii’s diverse climates. Many nut-bearing species like almonds and cashews were introduced but none really found popularity like the Australian macadamia nut.
Even though the first macadamias arrived here in the late 1800s, it took years for it to be seriously considered as a commercial crop. Then researchers developed many superior varieties and it wasn’t long before farmers began growing them commercially. Today, when folks think macadamia, they think Hawaii since the best varieties were promoted as Hawaiian macadamias even thought they are now grown in parts of Africa, tropical America and Australia as well.
Besides macadamias, let’s consider other nuts with potential here. Cashews fit well in the home garden. The nut or seed develops at the bottom of the cashew fruit. It is easily grown from seed and grows to be a small round-headed tree. Cashew trees are related to mango trees and have irritating sap so the seed must be handled carefully when processing. The juicy fruit is edible fresh or made into juice or even an alcoholic beverage.
At higher elevations, above 4,000 feet, pistachios and almonds may possibly be grown, but are not readily available at local nurseries. They may be specially ordered from California, however. Growing conditions that are cool and dry are best.
Getting back to the coconut palm, it makes a great tree for the Hawaiian garden. The dwarf Samoan form is the best and available at some local nurseries. The tree will start producing fruit when young and may be easily harvested at near ground level for years. Another advantage is that it is resistant to lethal yellowing disease that killed millions of trees in Florida and the Caribbean. These palms thrive below 1,500 feet elevation, but will not tolerate the long cool temperatures found above that elevation.
When was the last time you had pili nut pie, pili nut brittle or pili nut cookies? Unless you have lived in the Philippine Islands it is probably never. How about tropical almond cookies? Again, we don’t see them here but tropical almond confections are popular in Haiti and other parts of the Caribbean. The tropical almond, or false kamani (taxonomically, Terminalia catappa) is originally from the East Indies but now found all over coastal regions of the tropical Pacific.
Another delicious but rare nut here is the Brazil nut from the Amazon jungles. Bertholletia excelsa is known to help strengthen your immune system due to antioxidants present. Unfortunately, this tree is only found in a few private and botanical gardens. If you manage to locate a tree, don’t eat the nut. Germinate it. By the way, if you do have a tree or know where one is, please let me know.
One of the tastiest nuts found in the Philippines is the pili. The pili nut, Canarium ovatum, is native to the Philippines and is the most important of about 10 nut-bearing species. The tree reaches an ultimate height of about 60 feet. It can be easily kept lower by proper pruning. Leaves are compound like the African tulip. Flowers are yellow, fragrant and form in terminal clusters. Male and female flowers are born on separate trees, so two trees of opposite sexes are required to produce nuts on the female tree.
The oblong greenish fruits are black when ripe and are almost 2.5 to 3 inches long. The nut can be eaten raw or roasted and some consider it superior to the almond. The kernel is made into several products, including plain roasted nuts, sugar-coated nuts, pudding and pili nut butter. They are great in nut chocolates and are a source of a good cooking oil. Resin may be tapped from the tree as with the rubber tree. It is used in perfumes, adhesives, plastics, printing inks, paint, varnish and many other products.
The University of Hawaii College of Tropical Agriculture and Human Resources has studied pili production for years and found it to grow very well at lower elevations. It is a beautiful tropical tree that should be protected from strong winds and given irrigation where rainfall is below 50 inches of well-distributed rain per year.
The limiting factor in growing pili trees is availability of plants. Most trees in Hawaii and the Philippines are grown from seed. Grafting and budding are difficult. Air layering has limited success. Since the University does have a number of trees at the UH experiment station near Hilo, it would be possible to obtain seed by contacting our UHCTAR Agricultural Extension office there. Ask for one of the Master Gardeners to assist you. In Hilo the number is (808) 981-5199. Seeds are not always available, but may be obtained when in fruit.
Since 2024 politics make us all feel a bit pupule, it is a good time to get sane by planting a few nuts in your garden!
Norman Bezona is professor emeritus, University of Hawaii College of Tropical Agriculture and Human Resources.