Phillip Island Hibiscus

Hibiscus insularis (Phillip Island Hibiscus)

Norfolk Island has a wonderful small tree, and I enjoy watching the stunning flowers it produces. The tree is called Phillip Island Hibiscus. I have not been out to visit Phillip Island to see the tree in its natural environment, but I have found a few trees around gardens on Norfolk Island.

The first Phillip Island Hibiscus tree I saw, in 2011, when I first moved to Norfolk Island, was up Grassy Road at “In the Wild” in the grounds of the mini golf by the Captain Cook fountain. I enjoy watching the tree grow in the courtyard gardens at the Museum House Number 10 Quality Row. The flowers seem never ending during the spring, but I have read that the Phillip Island Hibiscus can flower all year round on Phillip Island and I expect they flower the same here on Norfolk Island. There are also a couple of Phillip Island Hibiscus trees at the Norfolk Island Bowling Club, it has little pretty flowers, and it is situated in the garden along the entry walkway heading to the clubrooms.

The Phillip Island Hibiscus is the common name for Hibiscus insularis. The Threaten Species Scientific Committee (TSSC) listed it as a Critically Endangered under the Australian federal environmental legislation in 2003.

There is more information available at the following link:

https://www.dcceew.gov.au/environment/biodiversity/threatened/species/norfolk-island-flora-critically

11 Critically Endangered Norfolk Island Flora Species - DCCEEW

11 Critically Endangered Norfolk Island Flora Species

Hibiscus insularis (Phillip Island Hibiscus) <50

Last updated: 03 October 2021

I learnt when I first saw the special tree that it was endemic to Phillip Island, which is the larger of the two islands to the south of Norfolk Island. I have been researching the information about the Phillip Island Hibiscus and found out that in 2003, there were fewer than 50 mature plants growing on Phillip Island. In 1988, Phillip Island Hibiscus occurred as two small patches with respective diameters of 10 and 50 metres. By 2001 a third patch 10 by 50 metres had become established. The species were confined to three patches on the northern slopes. The natural population has increased from previously recorded population levels. There were thirteen plants recorded in 1939, and only eight plants in 1963.

It was interesting to read that the study of the biology of Phillip Island Hibiscus (Groeneveld 1989) found that there was no evidence that the adult population consisted of more than one genetic individual. If this is the case, then the species is also at risk from extremely low levels of genetic diversity. Hopefully the genetics of the surviving plants are strong enough to continue for future generations.

Phillip Island was overrun by goats, rabbits and pigs which were introduced in the convict period of the early British settlement of Norfolk Island. These plants have survived despite the grazing animals which destroyed most of Phillip Island's vegetation. The introduced animals have now been removed from Phillip Island, seedlings are now growing near the original bushes.

The Norfolk island group has a subtropical climate, and the volcanic soils are nutrient rich, friable and porous. They do not hold moisture well, a few years ago my water tank liner broke and there was hardly a puddle on the ground after two weeks of leaking.

Phillip Island Hibiscus is a large shrub or small tree, and it can grow from 1.5 to 2.5 m high. The research described the leaves as lobed with a shiny upper surface and are 3–5 cm long and 2–4 cm wide.

A local Islander told me that she as a Phillip Island Hibiscus tree with very small leaves, so I found it very interesting to read that young seedlings have very small leaves, which develop into a deeply lobed juvenile form. This stage may persist for up to 20 years before the adult leaf form is produced. Since flowers are only seen once the adult foliage is present, Phillip Island Hibiscus has a long generation time.

My first attraction to the plant was the flowers. The Phillip Island Hibiscus flowers grow in an upwards fashion at the ends of branches. I read that they with rarely more than one flower at the same stage on the same branch. Large amounts of nectar are produced which you can see in some of my photographs. I read that the flowers are female when they first open, the yellow/cream greenish colour flower with a dark magenta centre and one day later they enter the male phase (at which point they are capable of self-pollination). Over the next few days, the flowers turn pink and fades to purple/mauve colours as they close up, then wither. Separation of the male and female stages by one day increases the opportunity for outcrossing.

Phillip Island Hibiscus is capable of producing seeds by self-pollination and is also capable of vegetative reproduction through the stems. Horticultural use of the Phillip Island Hibiscus has greatly increased the number of plants, even though not in its natural environment, but as it is usually propagated by cuttings the number of genotypes is still extremely small.

To safeguard the Hibiscus insularis propagated populations of the species are also located at the Botanic Gardens on Norfolk Island and in Booderee Botanic Gardens in Booderee National Park (formerly the Jervis Bay annexe of the Australian National Botanic Gardens) (ANBG 1988; Director of National Parks 2008).

It was very interesting to read about the threats to the Phillip Island Hibiscus. In the past, as mentioned above, it has been threatened by grazing and habitat degradation by the feral pigs, goats and rabbits that occurred on Phillip Island. However, these species have now been removed from the Island and no longer pose a threat to the native vegetation.

The greatest current threat to Phillip Island Hibiscus is the invasion of Phillip Island by African Olive, Olea europaea subsp. africana. African Olive competes with Phillip Island Hibiscus for water and nutrients and can grow as dense thickets which block the expansion of Hibiscus populations. When I first moved to Norfolk Island, I thought the Olive Tree was a native to Norfolk Island, as it can be seen widespread across most of the island.

Soil erosion on Phillip Island reduces the ability of native vegetation to recolonise areas of the Island. The Norfolk Island group sometimes experiences cyclones in the early months of the year. The lack of vegetation on Phillip Island makes the island more vulnerable to erosion during periods of heavy run-off. I have been told that the sea water surrounding Phillip Island would be red after heavy rainstorms with eroded soil washing in the sea.

I read about the threat and abatement and recovery plans. Several of the priority actions listed in the conservation of Norfolk Island would also be of benefit to Phillip Island Hibiscus. The restoration of native vegetation and the eradication of weeds are also listed as priority activities. Weed infestations have been reduced by removal of weeds and replanting with native species.

A couple of years ago, I saw this update on Facebook, posted by the Norfolk Island National Park. It is also wonderful to know that the Native Park Nursery is up and running, and they are successfully growing many natives including Norfolk Island Hibiscus which are available for the Norfolk Island National Park and for the community.

https://www.facebook.com/NorfolkIslandNP

Norfolk Island National Parks

Philip Island Hibiscus

Today for Biodiversity month, we will be taking a close look at the Phillip Island Hibiscus. This plant has only ever been found to grow on Phillip Island (a smaller island 6km offshore from Norfolk Island).

In 2003, surveys found only 3 patches of this plant on Phillip Island. And whilst there were around 50 wild plants in total, genetic testing revealed that these 50 were derived from just one genetic individual. This placed it in the realm of one of the planet's rarest plants.

Following this remarkable discovery in 2003, the national park embarked on significant endeavours to propagate it. Unfortunately, growing from seed is a very slow process, and it can take up to 18yrs for the plant to flower and fruit. However, when grown from cuttings, it is much quicker, leading to flowers being produced in just a few months.

Thanks to the care by the National Park, the Phillip Island Hibiscus now flourishes across Norfolk Island, with another stand successfully established on Phillip Island too.

Parks Australia

For more details.

check out this internet link

http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=30614

In October 2016 I first researched the information about the Phillip Island Hibiscus. I have enjoyed reading about the beautiful Phillip Island Hibiscus. I have taken many beautiful photos of the lovely flowers which I will share with the readers

Betty Matthew

29 August 2025