Articles

A Blue Flowering Winter-hardy Hibiscus

Blue Breed: Rare Hibiscus Color is Achieved Thanks to Flower Breeding Project,
ScienceDaily, September 2010

Dr. Dariusz Malinowski is seeing blue, and he is very excited. For four years, Malinowski, an AgriLife Research plant physiologist and forage agronomist in Vernon, has been working with collaborators Steve Brown of the Texas Foundation Seed and Dr. William Pinchak and Shane Martin with AgriLife Research on a winter-hardy hibiscus breeding project.

The project was first a private hobby of the inventors and became a part of the strategic plan of the Texas AgriLife Research and Extension Center at Vernon in 2009. The flower commercialization is a part of the research on non-traditional or under-utilized crops that have value because of drought tolerance.

Malinowski's breeding goal has been to create a blue-flowering winter-hardy hibiscus. "A blue pigment does not exist in this species, thus hybridizers have not been successful so far in creating a plant with blue flowers," he said. "There are a couple of recently introduced cultivars with plum and lavender flower color." But now Malinowski has managed to breed a flower with the illusive color.

He and his collaborators have created a number of lines with unique flower and foliage shape and color. The new hibiscus hybrids range in color from white through different shades of pink, lavender, bluish, red and magenta tones, and some of them have combinations of two or even three colors. One line has dark maroon foliage with moderately big, white flowers that blend into a pink center with darker veins, Malinowski said. Flower size of these hybrids varies from miniature blooms 2 inches in diameter to the size of dinner plates, about 12 inches in diameter.

Malinowski has been using these cultivars in his breeding project for several generations. This year, they finally had one plant bloom with almost blue flowers, a significant breakthrough in efforts to create a blue hibiscus cultivar. "It took four years of work and more than 1,000 crosses among three winter-hardy hibiscus species to achieve this goal of creating an almost-blue flowering hibiscus hybrid," he said. The new hybrid is not perfect yet, Malinowski said. "The flowers get a fantastic blue hue in shade, but in full sunlight they are still plum-lavender-bluish," he said.

Brown said it is important to note that in the world of ornamentals, "blue" is interpreted to have a wide range of hues. Most ornamental blues have a more purple or lavender cast. "There are very few true blue flowers in any ornamental cultivar," he said. "Although I would call this flower 'almost blue' as Dariusz has, there is no question that this development is unique in known hardy hibiscus color ranges. "My expectation is that we will see more vibrant colors in next year's F1s (cultivars) using this line as a parent," Brown said.

Malinowski said he will use this plant as a parent in his breeding project this summer, with the goal to stabilize the blue color in full sunlight and increase flower size from the current 7 inches to the "magic" 12-inch diameter.

Breeding of ornamental plants is not the major research area of Malinowski, but he said he enjoys new challenges and the benefits of combining his private hobby with business. "I never thought I would be an expert in breeding winter-hardy hibiscus," he said. "The knowledge I have gained during the past few years of intensive work on hardy hibiscus helps me reach most of the breeding objectives in a relatively short time."

What is next? Malinowski and his collaborators have a new challenge -- to create an orange flowering hardy hibiscus. This goal seems to be even more difficult, but not impossible, Malinowski said. It will require hybridization with a distantly related hibiscus species, which has shades of orange flowers. The researchers hope that with the help of molecular genetic tools they will be able to meet this objective.

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Texas A&M AgriLife Communications. The original article was written by Kay Ledbetter.

Hibiscus kokio subspecies kokio / Hibiscus kahilii

Endemic Pink Hibiscus Hails from Kauai, by Rick Barboza, December 2005

Description and distribution: The subspecies mentioned above is highly variable, having many different forms on Kauai, Oahu, Molokai, Maui and possibly Hawaii. Generally, each has dark green, glossy leaves with serrated margins and a pointed apex. The flowers are usually red and measure only about 2 to 3 inches in diameter.

This particular form, however, often referred to as Hibiscus kahilii, from Mount Kahili on Kauai, is much different. It has less glossy leaves, more lobed serrations on the margins and a rounded apex (young plants have pointed apexes that usually become rounded as they mature). The leaves cluster toward the stem tips, which adds to this plant's nice shape. The most striking feature of this form is its flower, which varies from a dark reddish pink to bright light pink.

Landscape use and care: Compared with most hibiscuses, this one grows slowly and is best adapted to moist areas. Few pests bother this plant. Whiteflies will occasionally appear under its leaves, and aphids might appear on leaf and flower buds. Both pests can be controlled with storebought pesticides.

If you are fortunate enough to come across this plant at a sale or store, it will make the perfect addition to your garden. I suggest planting it as a specimen plant rather than a hedge because of its growth habits and unique beauty. Well-drained, rich soil in full to partial sun is best for this plant.

Cultural use: Like most other native hibiscus, the flowers of this plant are eaten as a mild laxative and are occasionally used in leis.

Also: This is the only endemic "pink" hibiscus in Hawaii and is quite rare because it hails from a small population of plants on Kauai. There is another indigenous hibiscus (Hibiscus furcellatus), which has large pink-purple flowers. All other pink hibiscus plants are usually hybrids that are not native to Hawaii.

Rick Barboza co-owns Hui Ku Maoli Ola, a native Hawaiian plant nursery, with Matt Schirman. Reprinted from Honolulu Star-Bulletin, Vol. 10, Issue 336 -Friday, December 2, 2005

Hibiscus pernambucensis

Mahoe: Native or Exotic or Both?, By Dick Workman (Copyright 1998)

Out of favor in landscapes and listed as an invasive exotic, the sea hibiscus could be suffering from mistaken identity. There is, in fact, a species that may well be a Florida native.

With its big colorful flowers, fast growth, and salt-tolerance, the Sea Hibiscus -a.k.a. Mahoe- became a favorite South Florida landscape tree during the 1960s and 70s. Its ease of propagation -cuttings can be grown into six foot tall, ready to plant trees in just one season -made it popular with nurseries. And the professionals have long endorsed it as well. In their 1972 booklet, "Native Trees and Plants for Florida Landscaping", Charles Bush and Julia Morton featured the Mahoe, known by the scientific name Hibiscus tiliaceus, as a native to the southern peninsula and called it "a good tree for seaside landscaping."

But most stewards of natural systems in South Florida might wince at those endorsements. The Hibiscus tiliaceus they know is a pest plant listed by the Exotic Pest Plant Council (EPPC) as a category II pest species. When Mahoe shows up in natural areas it can form dense thickets of branches that are nearly impenetrable. Its water transported seeds often form thick stands at the upland edge of mangroves, eventually shading mangroves out of their habitat. It is this characteristic that got Hibiscus tiliaceus added to the EPPC list of invasives.

How could Julia Morton have been so right about Melaleuca, Earleaf Acacia and many other ornamentals turned pest-plants and so wrong about the Mahoe? While preparing a revision of "Growing Native", a book of native south Florida landscape plants written in the late 1970s; I asked that question of Drs. Derek Burch and Dan Ward, both respected Florida botanists. Dr. Burch told me told me there were several New World mallow family trees I should check out and Dan Ward suggested I look for Hibiscus pernambucensis, a Mahoe bearing yellow flowers without a red center.

I started searching unsuccessfully for such mahoe flowers. Then, while taking a group of students from Washington D.C. on an interpretive walk in the J.N. "Ding" Darling National Wildlife Refuge on Sanibel, we stopped at a planted row of Mahoe outside the refuge. I told them about the many practical uses of this tree, which had been introduced from the Old World tropics and, pointing to the flowers with red centers, asked for their help in spotting all-yellow flowers on their upcoming trip to the Keys. One of the students asked, "You mean like this one?" and indeed, there was a tree with yellow flowers and no red center.

After many trips back to this stand of trees to record what I perceived to be the differences, the confusion about Mahoe origins became much clearer to me. I sent specimens to Dr. Ward in Gainesville and to Dr. Richard Wunderlin at the University of South Florida and ended up connecting with Dr. Paul Fryxell of Texas A&M University via the internet. Dr. Fryxell, an expert on the Malvaceae, produced a major work on the plants of that family in Mexico. In his book, he cites the case for "splitting" the Old and New-World Mahoes and offers a list of distinguishable characteristics that justify the distinction between H. tiliaceus and H. pernambucensis.

I should note at this point that the photograph of the "native" Mahoe in the Bush and Morton book does not have a red center to its flowers. After checking several herbarium specimens of H. tiliaceus, I found that most lack the red center flowers. It makes sense that most specimens gathered for herbarium collections would have been gathered from natural areas where the majority of those trees would have been the New World species. I expect we will find that H. pernambucensis is indeed native to Broward, Dade and Monroe counties, but much work will have to be done before everyone will be convinced of this. In south Florida, both H. tiliaceus and H. pernambucensis are cultivated and not distinguished one from the other in the nursery trade.

The name, Mahoe, confuses things further. It is a corruption of the Spanish word, majagua, a common name for several unrelated trees used to make cordage. The common tree species grown in Florida grouped under this common name include:

The rapid growth rates and showy flowers of these trees have made them popular with impatient Florida home landscapers. But the primary reason these trees were moved around so much by primitive cultures has to do more with their extreme usefulness. They have been a favorite of coastal cultures around the world for centuries, since all four of these mallow family species have fibrous bark used to make various kinds of cordage and clothing -a property of great value to indigenous cultures.

After some processing, the bark of the Sea Hibiscus makes wonderful raffia-like fiber. Dr. Willard Payne, a retired botanist, is an expert at making mahoe bark into twine and rope. To do it, he peels the bark from trimmed Sea Hibiscus branches and immerses it in water for a week or two. This soaking process, called retting, allows microorganisms to eat the pulp away from the bark fibers and leaves paper-thin crossed sheets of fiber that are a delight to work with, according to Dr. Payne. Cordage made by twining these retted strands of bark together makes a nice strong rope. Unfortunately, it doesn't last very long if exposed to the elements.

Hibiscus tiliaceus is used for ropes, mats and fish nets in its native Micronesia in the South Pacific. And it is the primary fiber used to make "grass" skirts. The Polynesians introduced both the tree and grass skirts to Hawaii during the 19th century. The Hawaiians call the plant "Hau", and use it for cordage, as a base for leis and in their folk medicine, where its sap was valued as a mild laxative and an aid to women giving birth.

The plant is considered naturalized in Hawaii, as it is in South Florida, meaning that it can (and does) reproduce in the wild and grow without help from people. However, naturalized trees can cause problems for their new environments, since the Mahoe's growth habit is to sprout branches from the trunk near the ground. When these low growing branches touch the ground, they root and send new branches straight up through the canopy.

The H. tiliaceus Mahoe has wood that is light and strong and is prized for tool handles in Hawaii. It also carves very well and shrinks very little as it dries. The heartwood is an interesting light brown to olive green and turns very well on a lathe. An additional benefit to removing them from the landscape is that you can endear yourself to the craft community; connect with one of the fiberarts or woodworking groups in your area, and they'll provide consumptive and creative -uses of all the Mahoe you can supply.

Telling H. tiliaceus and H. pernambucensis apart is most easily done by checking the flowers. Both species produce very similar flowers that have yellow petals when they open in the morning and then change color throughout the day until they are dark red by night. But the Old World Mahoe's petals of the corolla are dark red at their base, providing a red center to the flower. And once the trees mature, their relative sizes set them apart as well; in the row of Mahoe on Sanibel where both species were planted at the same time, H. pernambucensis looks like a 1/2 to 3/4 scale model of H. tiliaceus.

Without flowers the best way to distinguish the two species is by examining the underside of the leaves for hairs. Most H. pernambucensis leaves have a fuzzy underside. With a hand lens you see stellate hairs over a dense mat of arachnoid (spider-like) hairs. The same kinds of hairs are present on H. tiliaceus leaves but they are far fewer in number. To the naked eye, these leaves appear glabrous instead of fuzzy.

Dr. Fryxell and others make a convincing case for treating these two Mahoes as distinct taxa. Natural area managers should make a point to learn to distinguish one from the other and adjust their management practice accordingly.

Dick Workman is the former director of the Sanibel-Captiva Conservation Foundation. He is president of the environmental consulting firm Coastplan, Inc.in Ft. Myers, FL.

References: Abbott, Isabella Aiona; La'au Hawai'i, Traditional Hawaiian Uses of Plants; Bishop Museum Press, 1992.
Bush, Charles and Julia Morton, Native Trees and Plants for Florida Landscaping, Florida Department of Agriculture and Consumer Services, 1972.
Fryxell, Paul A., Malvaceae of Mexico, Systematic Botany Monographs, Volume 25, The American Society of Plant Taxonomists, 1988.
Lamb, Samuel H.; Native trees and Shrubs of the Hawaiian Islands; Sunstone Press, Santa Fe, NM; 1981.
Payne, Willard w., A Glossary of Plant Hair Terminology, Brittonia 30: 239-255,1978.

Some notes on Hibiscus cameronii, by Geoff Harvey, Queensland, Australia

Hibiscus cameronii (Family Malvaceae), Pink Hibiscus

Tall, little branched perennial; leaves to about 11.5 cm long, 3-5, or 7 lobed half way to the base, rarely unlobed, lobes usually broadest above the middle, serrate; flowers solitary or in leafy racemes or corymbs, involucral bracts reduced to small teeth at base of calyx to 3.5 cm long, prominently 10 nerved, membranous, petals to 8 cm long, flushed pink above, with deeper rose or reddish-purple base, staminal column exerted; caps. 3 cm long, hirsute. Endemic to Madagascar. – (ref. Hortus Third)

I have grown this soft wooded shrub in 20 cm containers for a number of years. Plants bloom lightly from spring to early winter with a good seed set. My bloom colour is pink rather than apricot. Retired Sydney Nurseryman, Les Beers reports that scions of H. cameronii can be grafted onto H. rosa-sinensis with great success. The late Ross H. Gast was a respected authority on Hibiscus, who during the 1960’s was associated with the Los Angeles State and Country Arboretum at Arcadia, California. During this period he searched many parts of the world for new species and old forms of ornamental Hibiscus to be used in his breeding program. The American Hibiscus Society published “Hibiscus Around the World” in 1980 which is presented in the form of letters to Joseph W. Staniford, his collaborator at L.A.S.C.A. This book contains a wealth of information and may still be available from the American Hibiscus Society.

Below are selected quotes from the book concerning Hibiscus cameronii –

Page 6 – “On this trip, I hope to be able to see the true H. cameronii, for as you know, there has been a horticultural scramble on this one for over a hundred years, in fact, almost since its introduction into England from Madagascar in 1837. I am now convinced that the H. cameronii as described in most modern horticultural literature, is not the true cameronii, for as you know, this has been responsible for listing H. cameronii as one of the progenitors of the modern Hibiscus hybrids in a lot of literature on the subject, including my own. What has been erroneously called H. cameronii is the pink known by many names, Pauhi Bishop in Hawaii, and Versicolor in Southern California and Florida. It is very popular in Fiji and other Pacific Islands, and goes under many different names. (Editor’s notes – it is known as Rose Scott in Australia). Although certain reports from India indicate that H. cameronii has been crossed with H. rosa-sinensis, there is no proof that these crosses, too, were not made with the pink referred to above. Dr. Y. Tachibana of the Osaka Botanic Gardens reports that he has been unsuccessful in his efforts to cross the true H. cameronii with H. rosa-sinensis”.

Page 22 – “While Fiji has Hibiscus varieties not seen in Hawaii or elsewhere, some varieties common to all areas are grown there. In fact, the variety which we call Pink Versicolor in California, and is erroneously called H. cameronii, is perhaps the most widely grown Hibiscus in Fiji, if park, street and public landscaping in general are taken into consideration”.

Page 6 – (written from Brisbane Aust.) “My main interest in the Botanical Garden was the possibility that I could find the true H. cameronii, Knowles & Westcott. Paul Weissich of Honolulu told me he thought he had seen this elusive species in the Brisbane Garden, so when Mr. Caulfield confirmed this, I lost no time in getting to that part of the garden where it was growing. One look at the plants and the one bloom in evidence confirmed the fact that the early-day journals had described the species correctly, and that Indian and Hawaiian authorities, from Bulletin No. 29 down to contemporary references, had been confusing H. cameronii with what we call Pink Versicolor – a wide miss of the mark. Actually, the coloring is very close to the hand-colored prints of this species published when it was introduced into England from Madagascar in 1837. It is a mixture of light rose and buff, and there are prominently darker maroon blotches on the petals. It is a real little beauty. Although the seed pod of H. cameronii is covered with a hairy coating, the flower parts are exactly like those of H. rosa-sinensis”.

Page 66 – footnote at bottom of page – Later: “It is now well established that the variety called H. cameronii in Hawaii and some other areas is really Pink Versicolor. This is due to a publishing error in an early English horticultural magazine which pictured Pink Versicolor as H. cameronii”.

Page 79 – refers to Kew Herbarium Sheets – “My great surprise, however, were the sheets on H. cameronii. There were several forms of this- at least two of which had the same flowers as our H. cameronii, but with different leaves. As you know, our H. cameronii has deeply cut, 3-lobed leaves, although some are almost entire. One of the specimens at Kew had perfectly round leaves, with even, small serrations or “scalloped” edges; another had heart shaped leaves, but this one was called a shrub 8 to 10 foot high which, of course, ours is not. In the H. cameronii sheets, too, was a specimen called H. macrosolandra –HOCH. Which looked like our H. cameronii, but as I had no description of H cameronii for a close check, I cannot say”.

Page 82 – “in going over my notes, taken at the Kew Herbarium I found that in checking the H. cameronii material, there was one specimen that was first labeled H. rosa-sinensis crossed out and the words: “H. cameronii, Knowles and Westcott” written in. The flower was pink to green in colour – as nearly as I could tell from the specimen- and was 13 cm across. The leaf was similar to H rosa-sinensis. Perhaps this could have been the reason for this mix-up in H. cameronii which has resulted in both Indian and Hawaiian bibliography to refer to H. cameronii as cross compatible with H. rosa-sinensis”.

Page 84- refers to the Herbarium collection at Edinburgh Botanic Gardens Hibiscus collection – “There were 3 sheets marked H cameronii, all of which were definitely pink H rosa-sinensis, so it appears that the mix-up in this species is quite wide spread. I was able to see “Cienfuegosia gerrardii”, a near relative of Hibiscus, which Dr.Parks asked me to secure, if I could, in South Africa. It seems to be rare, thus not in cultivation, although it is supposed to be the type species for the genus Cienfuegosia”.

Page 107 – refers to the Kirstenbosch National Botanic Gardens in South Africa.-“I have always wanted to see H. pedunculatus, and I not only had the opportunity to do so, but also to collect a generous supply of seed. It is apparently quite close to H. cameronii – the leaf is exactly the same shape and texture. Also, it is a small woody shrub, only 1 meter high. The flower is pinkish to blue, only 5 cm in diameter. The staminal column was much like H. rosa-sinensis, insofar as I could determine. I think that this one will give us some fun in attempting to cross with both H. cameronii and H, rosa-sinensis”. Editor’s note- H. pedunculatus is common in Australia and for years has been grown by native plant enthusiasts as Hibiscus geranoides, an endemic Hibiscus from northern Australia.

Page 108. - refers to the Le Chelland Hotel, Mauritius. “The long driveway that led to the hotel was lined with H. schizopetalus, heavily laden with bloom. At least a dozen Hibiscus plants form the main planting around the headquarters. I noted several different forms of what we call H. Versicolor, were in bloom – pink, red and orange. Many of these were seeding profusely. (Editor’s note – H. versicolor is considered to be an F1 hybrid between H. liliflorus and H. rosa-sinensis.)

It is well established that the species native to Southeast Asia, and hybrids developed there, found their way to Mauritius very early. In fact, the first recorded crosses between H. liliflorus and H. rosa-sinensis, as early as 1828, were made by Dr. Charles Telfair, a British Army Doctor, who remained as a resident physician in Mauritius after the British took over the island. His hybrids, described in detail and pictured in water colors by his wife, were published in English horticultural magazines. Dr. Telfair was a dedicated plantsmen who collected plants throughout the Mascarene Islands, Madagascar and even the African West Coast, sending them to Kew Gardens”.

Page 113 – refers to the Botanical Gardens at Tananarive, Madagascar. - “Apparently he was ground manager. In perfect English, he asked if I would like to see H. cameronii, then led us to a shady area; nearby where there was a very large planting of H. cameronii set as a ground cover! As with other South Indian Ocean species, it was subject to heteramorphism, with the juvenile leaves deeply cut, while the mature leaves were round”. (Editor’s note – the leaves on my H. cameroni are always lobed. Refer to notes on Herbarium specimens above on leaf shapes at Kew and Edinburgh.)

Page 120 – “Regarding H. Versicolor- it would be my guess that it is a very early cross- either man-made or natural, of H. liliflorus and the common red – that is the single form of H. flora plena – known as H. rosa-sinensis”.

The final quote is from a personal letter written February 16, 1966 - “Any discussion used in Hibiscus hybridization should include mention of H. cameronii, native of Madagascar. Due to an early error in publishing, this species has been confused with a common form of H rosa-sinensis and thus accepted in several important reference books as one of the components involved in H. rosa-sinensis. In fact this “pseudo-cameronii was the primary basis of an extensive hybridization project in India, and it was used freely in Hawaii in the early days. But insofar as known, true H. cameronii has not been successfully crossed with H. rosa-sinensis or with any other of the species with which we have been working – although the cross has been attempted by many hybridizers, including the writer.

Hibiscus Insularis, by Colleen and Geoff Keena, Queensland, Australia

Hibiscus insularis (Family Malvaceae), Phillip Island Hibiscus

Hibiscus insularis, commonly known as Phillip Island Hibiscus, is endemic to Phillip Island in the Norfolk Island Group. Phillip Island is a small island approximately 6 km south of Norfolk Island, over 1,000 km to the east of Australia. It occurs only as small isolated subpopulations (W1). The International Plant Name Index indicates it was recorded as long ago as 1833 (W2). This long recognition has been no guarantee of protection. While most references note the struggle against feral animals such as grazing pigs, goats and rabbits, these have not been the only threats. Discussing Hibiscus insularis in 1914, one visitor wrote “a few plants still remain on the island, but those I saw were in a most unhealthy condition, being covered with coccids, aphides, smuts, and other blights and pests. They were obviously maintaining an unequal struggle with an unfavourable environment” (W3).

The threats to the continuing survival of this species continue (W1). The feral animals have been removed. Currently, the greatest threat is the invasion by African Olive (Olea europaea subsp. africana) which competes with Phillip Island Hibiscus for water and nutrients, and can grow as dense thickets which block the expansion of Hibiscus populations. As well, moth caterpillars (Pectinophora scutigera and Asinoplaca cosmia) have been found to inhabit the seed capsules and consume the seed. While this does not threaten current individuals, it reduces the ability of the species to produce viable seed to enable recovery and growth of the population. Soil erosion is yet another threat as it reduces the ability of native vegetation to recolonise areas. Further risk factors include cyclones that can be experienced in the early months of the year and the lack of vegetation which makes the island more vulnerable to erosion during periods of heavy run-off. Finally, a study of the biology of Phillip Island Hibiscus found that there was no evidence that the adult population consisted of more than one genetic individual. If this is so then the species is also at risk from extremely low levels of genetic diversity. Hibiscus insularis is now protected by Australian Government legislation. As the number of mature individuals is extremely low, with the total population recorded during recent surveys numbering less than 50, this species is currently listed as Critically Endangered under the Environment Protection and Biodiversity Conservation Act 1999 (W 4). With all the introduced animals now removed from Phillip Island, seedlings are now growing near the original bushes (W1). Control and eradication of weeds is being undertaken and the Park management will undertake aerial layering to induce vegetative reproduction and promote recovery of the species.

INFORMATION ON HIBISCUS INSULARIS

The following information is taken from the Department of the Environment, Water, Heritage and the Arts (2008) website (W1). This site provides detailed information, including references for the following.

Description: Large shrub or small tree to 2.5 m. Flowers are solitary and cream to light green coloured when they first open, with a dark magenta center, but turn reddish or purple as they age. The lobed leaves have a shiny upper surface, and are 3–5 cm long and 2–4 cm wide.

Population Information: Propagated populations of the species are 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). In 2003, there were fewer than 50 mature plants of Phillip Island Hibiscus 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 m) had become established. The natural population has increased from previously recorded population levels (13 plants in 1939, and only eight plants in 1963).

Habitat: The preferred habitat is difficult to determine given the impact of feral browsing animals on the Island. The Norfolk Island group has a subtropical climate. The volcanic soils are nutrient rich, friable and porous and do not hold moisture well.

Life Cycle: Phillip Island Hibiscus 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. “There is a marked difference between the juvenile and adult foliage shapes, with tiny round leaves gradually changing over ten years or more to the large leaf commonly recognised as a hibiscus” (W5). The flowers of Phillip Island Hibiscus grow in an upwards fashion at the ends of branches, with rarely more than one flower at the same stage on the same branch. Large amounts of nectar are produced. The flowers are female when they first open 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 close up, then wither. Separation of the male and female stages by one day increases the opportunity for outcrossing. This species is believed to be bird-pollinated, but it is possible that the original pollinating species has become extinct. It is capable of producing seeds by self-pollination, and is also capable of vegetative reproduction through stem-layering.

PROPAGATION: Some references indicate that propagation can be from seed (P1, p. 375; P2, p. 76), however given the time for the life cycle, cuttings seem preferable. These can be firm wood cuttings taken in late spring (P2).

CULTIVATION: While Hibiscus insularis has not fared well in its original habitat, cultivation has ensured its place in horticulture. It is included in the temperate house at Kew Gardens: “Hibiscus insularis, with its many little gentle flowers, appearing somehow generous in an 'arms outstretched' sort of way” (W6). It is also described on a French (W7) and Canadian site (W8).

DESIRABLE FEATURES: There are a number of features that make this plant desirable in horticulture: the dense bushy form; the tiny, neat leaves; evergreen; disease-free; tolerant of wind; tolerant of full sunshine or partial shade; blooms are produced freely; changing colour of the blooms, with both coloured blooms at the one time; bright crimson stigma pads are very pronounced for a small flower; light pruning only is required to keep the plant in a nicely rounded shape; suitable for hedges; bird attracting because of the amount of nectar the flowers produce; easily grown; lack of prickles.

VARIATIONS IN FLOWERING & WATER REQUIREMENTS ACCORDING TO LOCATION

Jerry Coleby-Williams notes Sydney’s warm-temperate, sub-coastal humid climate is ideal for Hibiscus insularis because the climate is very similar to that of Phillip Island. He writes that the Royal Botanic Gardens, Sydney sent seed and cuttings from about nine adult plants growing in their collections to Phillip Island (W9). In Sydney, Hibiscus insularis plants at the Royal Botanical Gardens were grown from 15 cm cuttings taken in late summer. Eighteen months later, after the plants had been in the ground for a year, they were 1.2 m high (W10). We have seen Hibiscus insularis thriving and blooming freely in Port Macquarie, N.S.W. It performs well still further north in sub-tropical locations such as Brisbane and the Brisbane Valley. As well, it is recommended for planting in Mareeba in North Queensland (W11). While Hibiscus insularis performs well across a range of locations, the actual location where plants are grown seems to mean differences in flowering and in water requirements.

Flowering: In ‘The ultimate Hibiscus ?’, Jerry Coleby-Williams notes that in Sydney this species flowers for up to nine months of the year and while it flowers for an extended period, it doesn’t flower in one huge burst of blooms. However, in his garden in Brisbane, he notes the plants set loads of flower buds in readiness for show time in late winter to early spring (W12). This is the same in the gardens where we have grown it, both in the western suburbs of Brisbane and in the Brisbane Valley. When plants start flowering, and this has been at least ten years in both gardens, then there is a stunning display at the end of winter and in early spring. No flowers are seen at other times.

Water requirements: It has been noted that Hibiscus insularis performs in all but poorly drained soils (P2) and that it needs to be regularly watered (W12). I suspect that there may be a difference between the water requirement of seed-grown and cutting-grown plants; possibly due to differences in the root architecture. I have found seed-grown plants perform quite well with no supplementary watering other than in extreme conditions. Our plants were watered only once even at the height of the recent drought yet the following flowering was stunning. Here cutting-grown plants droop in dry conditions.

Extreme Conditions: It has been noted that plants are damaged by frost (W12). We have found they can survive light frosts but at around -5 °C, the buds on exposed parts of the bushes are damaged and fall off although buds protected by overhanging foliage can reach maturity. As the plants can take both full sun and partial shade, providing protection from summer heat and the cold of winter may mean the plant will be less affected by extreme conditions.

Fertilising: Our plants are grown as part of an informal garden, with paths meandering among the plants. The plants are such a feature when in flower that one path leads straight to one of the bushes. The plants are mulched with sugar-cane mulch but don’t receive any fertiliser. However, if the plants were to be grown in a more formal manner, the fertilising regime documented by Jerry Coleby-Williams should be noted. He feeds his plants once a year with a pelletised, blended, organic fertiliser in autumn and once every month the plants get a foliar feed with liquid seaweed (W12).

Differences in cultivation and in the wild: As with other Australian hibiscus, cultivation means that the plant may perform quite differently from plants in the natural environment. In the wild this plants makes a largish, spreading shrub with beautifully layered branches and neatly serried rows of tooth-edged, little leaves. Pruned as a shrub they reach 3 or so metres high and 4-5 metres wide. Allowed to grow as a tree they’re often multi-trunked, see Figure 8, with a broad arching canopy, reaching to 4 or so metres high and 4-5 metres wide. Storms can break tree branches when in flower (W12).

NEW USES

Hibiscus insularis is listed by Ergon Energy as a ‘Plant Smart’ tree suitable for Mareeba Shire (W11). Les Beers and Jim Howie (P2) have noted that the plant is ideal for growing in coastal areas as it is reasonably salt resistant. They also note that it makes a fine hedge plant and windbreak. Its use as a hedge plant to create a semi-formal, flowering hedge has been explored by Jerry Coleby-Williams. He has planted a hedge of Hibiscus insularis for some shade and shelter at the front of his garden and says that when the hedge is in full flower it stops traffic (W13, W14). He writes that there are many more side branches on this than on most other hibiscus species and that this is important when selecting a plant to create a hedge. His hedge has one annual cut after flowering that allows it to be shaped semi-formally and this cutting back means flower buds are initiated for the next season (W12). The tips of the bushes need to be pinched out to encourage bushiness (W10).

ILLUSTRATIONS AND ART: A specimen of hibiscus insularis was sent from Norfolk Island to be identified at the Commonwealth Forestry Bureau in 1933. An image of this specimen can be seen online (W15). The beauty of Hibiscus insularis has been depicted on stamps such as a 1d stamp in 1960, a 1c stamp in 1966 (W16), a 35 c stamp in 1984 (W17) and a 45 c stamp in 2002 (W18). Artists such as Ida McComish (1885-1978) have painted Hibiscus insularis. Her 1937 painting is held in the National Library (W19). Botanical artists such as Halina Steele have also painted Hibiscus insularis (W20).

SUMMARY

Hibiscus insularis is not just a beautiful plant for those of us who like to grow or illustrate native hibiscus. Its continued existence is due to ‘cultivation, conservation and education’, all of which are valued by members of native plant societies.

REFERENCES:WEB
W1 Department of the Environment, Water, Heritage and the Arts (2008) http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=30614,
W2 Prodromus Florae Norfolkicae 1833. http://www.ipni.org/
W3 Transactions and Proceedings of the Royal Society of New Zealand 1868-1961. Volume 47, 1914 http://rsnz.natlib.govt.nz/volume/rsnz_47/rsnz_47_00_000660.html
W4 Critically Endangered Norfolk Island Flora Species http://www.environment.gov.au/biodiversity/threatened/species/ norfolk- island-flora-critically.html
W5 http://www.environment.gov.au/parks/norfolk/nature-science/plants-of-interest.html
W6 http://www.bbc.co.uk/dna/h2g2/A431263
W7 http://www.cbnbrest.fr/site/html/visite/serres/oceanique.htm
W8 http://www.ontariogardening.com/Knowledgebase/speciedetail.jsp?id=2258
W9 http://www.rbgsyd.nsw.gov.au/welcome_to_bgt/annan/the_garden/blooming_calendar/annan_blooming_template31
W10 http://www.abc.net.au/gardening/stories/s204712.htm
W11 http://www.ergon.com.au/network_info/vegetation_management/downloads/32326_Mareeba_DL.pdf
W12 http://jerry-coleby-williams.blogspot.com/2006/08/ultimate-hibiscus.html
W13 http://www.abc.net.au/gardening/stories/s1310644.htm
W14 http://www.abc.net.au/gardening/stories/s1705928.htm
W15 http://uncommonlives.naa.gov.au/contents.asp?cID=73
W16 http://library.puc.edu/pitcairn/norfolk/philately-norfolk.shtml
W17 http://www.plantstamps.net/stamps/norfolk_island/1984_Definitives_Flowers/1984_hibiscus_insularis_s.jpg
W18 http://www.stamps.gov.nf/stamps2002.htm
W19 http://www.nla.gov.au/exhibitions/fence/picket_6.html
W20 http://www.bellis.info/Bellis/Blog/Entries/2008/6/28_Entry_1.html

Hibiscus insularis - juvenile form

Food Safety of Australian Plant Bushfoods, by M.P.Hegarty, E.E. Hegarty, 2001

Hibiscus heterophyllus, (Native Rosella) and related species.

Natural Distribution: Coastal regions of Queensland and NSW

Varieties and forms: Native Rosella is an extremely variable species, and natural and induced crosses with other species are very common. Confusion with Hibiscus divaricatus is common (Keena 1997). Hibiscus heterophyllus is sometimes described as a complex of species, and the overall flower colour and distinctive markings can range from white to a wide range of pink and red tones (Wilson & Craven 1995).

Parts used: The flower petals are used to colour and flavour beverages, baked dishes, salads and desserts. The flowers have larger petals than the better-known wild rosella (mentioned below) from which the more conspicuous calyces are selected for use in foods. Nutritional values for the flowers, and those of H. diversifolius and H. tiliaceus, are given in Brand Miller et al.(1993)(see Appendix 1).

Traditional uses: The Aboriginal people of North Queensland ate the roots of young plants, young shoots and leaves of H. heterophyllus. The buds and the peeled, thick, starchy but fibrous roots of the related species H. divaricatus were also eaten. (Bailey 1899; Weston 1998). A decoction of Hibiscus was used to ease the symptoms of coughs and colds (Cribb & Cribb 1974 p.222). The sour leaves of H. heterophyllus were known as native sorrel by early European settlers and having been boiled to lose their acidity, used as a substitute for spinach (Low 1989).

Scientific studies:

(a) General. Apart from the analysis of nutritional constituents (Brand Miller et al.1993) the chemistry of this species does not appear to have been studied extensively. It might be expected to be similar to that of other tropical Hibiscus species for which some records are available. The mucilaginous flowers, used in jam, contain pectins, but require the addition of acid in some form. The jam is always a brilliant rosella colour regardless of the original colour of the corolla (Wrench 1998). All tests for alkaloids in leaves of H. heterophyllus and four other native Hibiscus species (Collins et al. 1990) were negative, as were two tests of the leaves and stem of H. diversifolius from Mt Coot-tha, Qld. (Webb 1948). A different test method during this latter study gave a positive result, which might have been due to the reaction of the reagent with starch in the plant (Webb 1952).

(b) Toxicological. Cribb & Cribb (1974) assert that "any hibiscus is almost certainly safe to eat". However, the seed .pod. of some species is covered in sticky hairs that may cause skin irritation. They may be removed from the skin with sticky tape, and the seeds should be extracted from the pod with tweezers (Keena 1997). There do not appear to be any reports of adverse effects from consumption of products from the flowers or buds and calyces in foods. There has been a single anecdotal report that very frequent use of the leaves to make infusions resulted in some form of kidney damage, and it is known that Aboriginal people used the plant sparingly, more as a medicinal plant than a food (Barker 1995). However, numbers of people have used the leaves in infusions over long periods without untoward effects. Some of the potentially bioactive compounds in various Hibiscus species (Duke 1992a, b) are not readily water-soluble and so would not be present in infusions unless the crushed leaves themselves were included.

Maiden (1889) and later authors including Watt & Breyer-Brandwijk from Africa (1962) and those cited by Cambie & Ash (1994), have noted that the juice of the leaves of H. diversifolius (a very wide-ranging and somewhat variable species) had been used to procure abortions in Fiji. Some, if not all, such mentions appear to be based on a single report by Seeman on a Government mission to Fiji in 1860-1861. With the passage of time, the possibility of such activity appears to have been more or less discounted (Webb 1948; Cambie & Brewis 1997).

SOURCE: Food Safety of Australian Plant Bushfoods By M.P. Hegarty, E.E. Hegarty. 2001