Islands are Nature’s kitchen and the Hawaiian Islands, sitting in splendid isolation in the middle of the Pacific Ocean, are the perfect place to see where evolution has cooked up a smorgasbord. When the first humans arrived on the islands around 400 AD there were already thousands of plant and animal creations.

Over 90 percent were endemic (found nowhere else in the world), having evolved over millions of years from ancestors who made the precarious journey across thousands of kilometres of open ocean. As it was just as hard to get off the islands as to arrive there, the 1,000 or so original species thrived and diversified, in isolation, free from predators and other selection pressures.

The original humans, sea-faring Polynesians, brought everything they needed to establish settlements. They brought clothing and crop plants, livestock and the very first land-based mammals the islands had ever seen – pigs, dogs and chickens. For more than ten centuries their rich agricultural tradition slowly made its mark of Hawaii’s natural ecosystems.

Human impact intensified after European contact. On his great voyage of discovery, James Cook and his party landed at Waimea on Kauai on 18 January 1778.

Kealakekua Bay, Big Island. Cook met his death here a year later.

This international exposure started an irreversible influence that would see plantations flourish all over Hawaii and bring economic prosperity to the islands. Plantations of sugar, pineapples, coffee, commercial timbers, macadamias, gingers and even rice were developed extensively through the 19th and 20th centuries.

As Hawaii exported these staples to the world, more land and workers were needed to meet global demands. This resulted in massive land clearing (and degradation as thirsty crops depleted natural resources) and an influx of immigrants that would make Hawaii the cultural melting pot it is today.

Human impact continues as we now mould contemporary Hawaii into our vision of a marketable tropical paradise. The thriving export industries are almost gone but some older and better-established plantations have been turned into tourist attractions with historic museums, special tours, good food and great gifts. Many are set in beautiful gardens.

Peter and I passed this small pineapple plantation on our trip across Oahu on our way to a wedding. We didn’t have time to visit the Dole Plantation of which this is a part. It has reinvented itself as Hawaii’s ‘Pineapple Experience’ and, in 2008, its giant Pineapple Garden Maze was declared the world’s largest maze.

On the Big Island we saw similar small holdings for the commercial production of coffee, macadamia nuts and Plumeria (frangipanis) flowers for leis.

Another thriving tourist industry in Hawaii is botanic gardens. There are almost 40 public gardens and arboreta across Big Island, Oahu, Maui and Kauai – an amazingly large number for such a small land mass. Hawaii has so many different microclimates that plants from the tropics, temperate and arid regions of the world can easily be cultivated.

Many botanic gardens started out as private gardens often around plantations or on degraded land. Others were created as scientific collections linked to academic or agricultural institutions. All seem to have been labours of love, passionately created by visionary individuals with artistic and horticultural expertise.

The raison d'être behind each garden is reflected in the plants found growing in them. Some focus on conservation of native plants and Polynesian introductions (canoe plants), while others feature colourful displays of exotic flowers and tropical foliage.

If, like me, orchids are your thing then you’re spoilt for choice. For my orchid ‘fix' we visited the Hawaii Tropical Botanical Garden on Big Island. A short drive from Hilo, this is truly a plant lover’s paradise and we spent many hours here.

Rhyncholaelia glauca (‘H7R’ x ‘Woltman’), , Hawaii Tropical Botanical Garden.

Themed orchid garden, Hawaii Tropical Botanical Garden.

This is an example of a private garden built on land degraded by early settlement. These images in the visitor’s centre show what the area looked like in the 1800s before reforestation.

Sugarcane plantations covered Onomea Bay in the mid-1800s.

Interpretive signage explains how, in 1977, Dan and Pauline Lutkenhouse, having sold their trucking business in San Francisco, fell in love with the beautiful Onomea Valley. They bought an old house and a 17-acre property that extended all the way down to the ocean. It was ‘so overgrown that a machete was needed to walk only a few feet through it, and filled with old cars, machinery, appliances and trash of all kinds …’

Dan’s dream was to create a welcoming garden of serenity that would forever preserve this awe-inspiring ocean valley and house rare tropical plants. They cleared, designed, collected and planted, built a lake, discovered hidden waterfalls and carved out aesthetic trails. In 1984, they opened their landscaped rainforest ravine to the public and showcased over 2,000 tropical species collected from around the world. Dan and Pauline then donated this valuable land and garden to a charitable Trust on which they both served until their respective deaths in 2007 and 2017. The garden attracts millions of visitors annually and thrives on visitor admissions and small private donations.

I particularly enjoyed this garden because the founders’ passion is palpable and the biodiversity on display is outstanding. It’s easy to navigate the trails (even though some are steep) and there are extensive collections of palms, heliconias, ferns, anthuriums, bromeliads, orchids and many other plant groups.

All this and more under the protective canopy of magnificent trees such as monkey pod trees, tropical almonds and ironwoods. This is what botanic gardens are all about – passionate gardeners growing and interpreting nature’s encyclopedia of plants.

Every trunk has an epiphyte attached to it and even moisture-loving fungi show off their biodiversity.

I had my fill of orchids here and was delighted to come across knowledgeable staff to identify for me an orchid we found growing ‘like a weed’ on roadsides. It’s another of Hawaii’s naturalised ornamental garden plants and it’s even for sale in their gift shop.

Hawaiian Bamboo Orchid Arundina bambusifolia — Hawaiian Bamboo Orchid *Arundina bambusifolia*

Basically, Hawaii is full of introduced plants. Many are welcome as ornamentals but a few have become serious environmental weeds.

Gingers are beautiful in gardens but some, like Kāhili ginger (Hedychium gardnerianum), have become forest pests. We saw huge heads of its striking yellow flowers and smelt its exotic fragrance are all over Hawaii’s islands. Unfortunately, it is extremely invasive and tends to grow quickly, choking out native plants. FYI, this ginger is also regarded as an environmental weed in Queensland and New South Wales.

Roadside Kāhili ginger (Hedychium gardnerianum) at Volcano, Big Island. — Roadside Kāhili ginger (*Hedychium gardnerianum)* at Volcano, Big Island.

Princess flower Tibouchina urvilleana on roadside at Volcano, Big Island.

The Princess flower (Tibouchina urvilleana) is a familiar ornamental in our Australian gardens yet in Hawaii it now grows wild.

Tibouchinas belongs to the Melastomataceae family. This moderately large family of over 4,500 species occurs widely in warm and tropical regions of the world. Of those found in the Hawaiian Islands, the majority don’t present any major problems. For example, Medinillas are non-invasive shrubs with spectacular pendulous blooms shrubs. Medinilla magnifica has achieved the Royal Horticultural Society’s Award of Garden Merit.

But one member of this family is a notorious weed. The Velvet Tree (Miconia calvescens) is called ‘green cancer’ in Tahiti and the ‘purple plague’ in Hawaii. I already knew of this Miconia’s well-deserved reputation as it is listed as one of the ‘100 of the World’s Worst Invasive Alien Species’ by IUCN.

It was introduced into a botanical garden in Tahiti (French Polynesia) in 1937 and was first recorded as invasive in the early 1970s. The species now grows on 70% of that island with one-quarter being covered by dense monospecific stands. Miconia was similarly introduced to Hawaii in the early 1960s and has already become a serious weed. Sadly, Peter and I spotted it extensively on the Big Island where it exists in dominant clumps that smother and displace native vegetation. It is reported to have made a similar impact on Maui but is still confined to localised areas on Oahu and Kauai.

Dominant clumps of Miconia. Miconia can grow 15 metres tall.

Pest control operations exist in many tropical regions of the world and Hawaii has established island-based Invasive Species Committees. Hawaii Invasive Species Council gives a chilling account of Miconia’s distribution.

Even Australia has a national eradication program for Miconia. It was introduced in Townsville in 1963 and now has naturalised populations in far north Queensland and small infestations have been found as far south as the Tweed and Byron Shires on the north coast of NSW.

It’s important to appreciate that not all introduced plants and animals become invasive and species dispersal is a fundamental and necessary component of evolution. Botanic gardens may have been responsible for some weed introductions but they are also the best places to develop a conservation ethic in contemporary society along with an appreciation of plant diversity.

This segues nicely into the sterling work of the National Tropical Botanical Garden (NTBG). In 1964, NTBG was created by United States Congressional Charter as a not-for-profit institution, dedicated to tropical plant research, conservation and education.

In its short fifty-year history, it has developed five public gardens (three on Kauai, one on Maui and one in Florida) as well as a Botanical Research Centre which opened in 2008 at its headquarters in Kalaheo, Kauai. The gardens are major tourist attractions and house the largest collection of native Hawaiian plants in the world.

Juliet Rice Wichman Botanical Research Centre.

At the Botanical Research Centre, I managed to see herbarium specimens of Hawaii’s only native orchids – three very rare species (Anoectochilus sandvicensis, Liparis hawaiensis and Platanthera holochila) that only grow in the highest reaches of the islands’ forests and bogs. Platanthera is the rarest of them all and is considered one of the most endangered orchids in the world. It’s strange how Hawaii is well known for its orchid diversity yet these are exotic species and their endemic cousins are close to extinction.

Dr Ken Wood showing me Herbarium specimens of Hawaii’s three native orchid species.

I realised half my interest in the world of botanic gardens is because they attract interesting people who are fascinated by nature’s wonders and are passionate about making a difference. NTBG was literally dreamed into existence by prominent individuals including David Fairchild, Joseph Francis Charles Rock, Robert Allerton, Henry Francis DuPont and many other colourful characters in the history of plant exploration. These gardens are so young that many of the current staff are pioneers in their own right.

Another optimistic environmental achievement is NTBG’s research into Polynesian cultural knowledge of breadfruit to address global hunger. Dr Diane Ragone, director of the Breadfruit Institute, had no idea the global impact her discoveries would have when a grant took her to remote areas in the Pacific Islands 30 years ago. Visiting farms and gardens in backyards on the Cook Islands, Tonga, Tokelau and other islands in the Pacific, she collected breadfruit samples from more than 200 varieties, some very rare. She found the texture, taste and nutritional value was better in some than others.

NTBG now cultivates 130 kinds of breadfruit, the most extensive collection in the world. Its research and international collaborations have identified the best breadfruit varieties to grow and feed the hungry in 16 countries, including Nicaragua, Tanzania, Costa Rica and Ghana. Ragone says “Our work has the potential to have a global impact on food security and hunger.”

Like taro, breadfruit is a canoe plant recognised by sea-faring Polynesians and Europeans as an excellent food and source of Vitamin C. Throughout the Pacific it is primarily grown for its edible starchy root and leaf vegetable. Its sheer size, high protein and fibre content make it a powerful staple in tropical areas. The tree grows vertically and is very productive even in small areas producing fruit through most of the year. It is easy to grow, requires very little fertilizer and irrigation, and produces abundant food for a family and community.

In 1769 Sir Joseph Banks said:

“regarding food, if a man plants 10 (breadfruit) trees in his life he would completely fulfil his duty to his own as well as future generations …”

NTBG also provides a safe haven for many endangered and extinct-in-the-wild tropical plant species, especially from the Pacific region. NTBG is the research home to tropical scientists worldwide who understand that tropical plants are the key to our survival on this planet and with one third of them threatened with extinction, they have plenty to do.

© Janelle Hatherly

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Hawaii: a paradise for plants

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