향기 무궁화 호주논문Hibiscus International vol 3 no4 2003- H. arnottianus, 호주 Colleen Keena from Queensland

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By: Jim Purdie

I would like discuss the subject of pruning your plants. The ideal time to be thinking about carrying out this exercise is in the Spring which coincides with your plants beginning to start sending out new growth as the weather starts to warm up after the cold winter months.

This is brought about by a few things the most important being that daylight hours begin to get longer as the sun on its journey begins to get closer to your country where you live, be it in the northern or southern regions of the world.

Also, as it gets closer, the weather begins to warm up and this causes the sap to flow and in so doing it causes the roots to start to draw more nourishment from the soil. This causes the plant to go into a growing mode with new shoots beginning to appear at the eyes on the mostly bare sticks we have seen during the winter.

Volume 3, Number 4               Hibiscus International                   August-October 2003

Always make sure, if you live in areas where you experience frosts, not to do your pruning until the danger of frosts have passed as frost will burn off the tender new shoots.

We prune our plants for a variety of reasons. I will list the most important reasons that we have to prune for:

1. To train a plant or bush into a desired shape.

2. To maintain the bush to a manageable size and open up the bush to the sun by pruning away the middle branches which have grown into the middle thus blocking out the air and light.

3. It helps in the control and to be able to see any attacks of insects more easily.

4. It will encourage stronger growth. As branches are shortened when you prune them, it will cause the plant to send out more branches and if you have more branches you have a better chance of obtaining more flowers.

5. Pruning gets rid of old and weak branches and those which have grown in a crisscross fashion causing a cluttered plant and all those that have grown out of shape.

6. If you prune your plants in the Spring you help the bush to promote larger and better blooms, of good shape and size. Hibiscus thrive on being pruned in the Spring and you do not have to get a step ladder to see the flowers when the branches get too long. When you prune the tops of the branches, it causes the plant to start shooting down lower and instead of bare sticks you will see a plant covered in nice green leaves and more branches. As I have said above, more branches means more flowers. This happens because when you prune the tops off, it stops the growing cycle from the tip.

Whenever I start to prune I try to think how the bush grows and prune the plant according to the way it grows. By that I mean if the plant is an average grower, I will prune off about a third of the bush. If the bush is a tall fast grower I will  prune off  about  a half  and  if  the  plant  is a slow low grower I will only just prune the tips otherwise it takes too long to recover if you give it a hard prune and you will miss out on the flowers for that season and have to wait until next year to see some blooms.

Volume 3, Number 4               Hibiscus International                   August-October 2003

I always cut off the low lying branches usually leaving a 12 inch space under the bush which allows you to keep things clean under the bush and also if there are low lying branches, if a flower come on these branches it drags in the dirt and there is a danger of snails causing damage to the petals.

Volume 3, Number 4               Hibiscus International                   August-October 2003

I prune just above an outward pointing eye, using a slanting cut away from the eye, so any water will run away from the eye, and also it encourages the new shoot to grow outwards instead into the middle of the plant, and I always try to end up with a pruned bush, which is in the shape of a vase. Make sure your secateurs are kept clean and sharp, so they will give a clean cut, and I like to dip my secateurs in some alcohol or methylated spirits between bushes to prevent spreading any disease.

Some members do not prune all the branches at one time so they are able to still have blooms while they wait for the new growth to flower. These remain-ing branches can be pruned once the new growth commences flowering.

If you are growing in pots this is a good time to think about doing a root prune at the same time as you prune the top of the plant, and repot into some fresh potting mix, with some slow release fertilizer included in the mix, either into the same size pot if it is the biggest you want to go to, or the next size pot if it is in a smaller pot.

When the bush is putting out a lot of new growth this is the time when I apply fertilizer high in nitrogen to promote new growth and apply this until you see new buds starting to form and then I start to use a fertilizer higher in potash than nitrogen to promote flowers instead of nice green leaves.

The fertilizer mix I use after pruning, for the plants I have in the ground, is one that I mix myself, and is as follows:

    a.     2 ice cream [ 2 litre ] cans of Blood & Bone;
    b.     2 of Super Phosphate;
    c.     1 of Sulphate of Potash;
    d.     ½ of Magnesium Sulphate or Epsom Salts; and,
    e.  ¼ of Sulphate of Iron.

mix all this well together and apply a good handful around each bush. Then I cover this with a good cover, about 2 to 3 inches, of a suitable mulch. This will keep the roots cool in the hot weather to come.

If you follow these instructions you will be on your way to having a nice healthy bush with plenty of flowers.

A "good bush" means different things to different people. In Europe it is basically a compact, natural branched plant which when pruned responds with several new branches. In the US and 0z, it needn't necessary be that compact, is considered generally acceptable if it forms a nice bush with proper pruning; hence, needn't necessarily be a good natural brancher and two branches per pruned stem is I think think considered OK. Now both of these "good bushes" are generated by slightly different needs based on climate, growing condi-tions, etc. However, it has occurred to me that in the past the interpretation of a "good bush" is too narrow. For example, I can envision special purpose bushes such as hanging baskets, the patio, etc. in which case neither of the above "good bushes" would be ideal on a patio. I could well envision a plant which cascades over the side of the pot making a mound of greenery with blooms. If one can develop a similar type bush of small enough size, it might be adaptable as a hanging basket plant.

My point is that I think it is worth considering hybrids with growth habits that do not fit the classic garden variety profile. For that reason I'm saving a few of those Miss Liberty seedlings that have inherited what is considered the worst of Miss Liberty qualities, i.e., a bush that has curling or spiraling branches that fall over the edge of the pot.

You won't want such a plant in your garden, but might find it very attractive on the patio, around the pool, on a terrace or in an apartment where you want low profile color.

This brings to mind another aspect of a cv bush type. Miss Liberty, again as an example, is a notorious floppy bush, but if you grow it like Allan Little does (Photo, left inset: Persephone Standard Bush: Allan Little © 2002), it is respectable and compares favorably to the typical "good bush" form, although still perhaps not ideal.

What I'm getting at is that a cultivar may or may not have a typical growth habit and in many cases, it varies from one bush of the same cv to another. I have several cultivars for which I have double and triples of the same plant, essentially all grown and pruned similarly, yet I find different growth habits.

Red Snapper for instance has two growth forms for me: 1) an open rigid bush with lateral somewhat twisted branches with pom-poms of leaves at the end and, 2) one with vertical growing better foliated branches, which needs support. Same cultivar, two different appearances.
Now if I were trialing this cv and only had one plant, I might come up with two entirely different opinions of its growth habits. Another example, as I mentioned recently, I have a heavily pruned Rum Runner both because of the demand for wood and because it was growing into an awkward bush with lateral branches. Now, I can hardly imagine a HOTY candidate of the stature of Rum Runner having been considered for a HOTY award if it had the growth habits of mine. (Right top photo: Gabriela bushed in pots: C. Quirino © 2002).

Volume 3, Number 4               Hibiscus International                   August-October 2003

I also have several others with duplicate plants - Improved Crimson Ray, Dragon's Breath, Fantasy Charm, High Voltage, to name but a few, and in every case one particular plant for a given cultivar will have a notably nicer classic bush type" than the others of the same cultivar, which all goes to point out that there is some variability, even significant variability, in bush type for a given cultivar.

We've had occasion to talk about this before, i.e., Black Knight and Eva Paoloni - which are for most people not ideal bushes, but for others are quite acceptable. I know, when we talk about the bush type of a given cultivar, we are talking about averages, but the above will perhaps serve as food for thought concerning the subject of hybrid-izing and the significance of bush type (Photo, left inset: Mellie May bush from Greg Lindsay: R.Johnson © 2002).

I suspect that if we would get the opinions of beginning hibiscus growers, especially those that grow in pots and in confined spaces, e.g., an apartment, their ideal bush type may not be that which is generally considered best and based on the typical garden variety profile, i.e., as an in-ground plant for the garden.

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Volume 3, Number 4               Hibiscus International                   August-October 2003

  

Hibiscus splendens

H. diversifolius

Hibiscus tiliaceus

H. ‘Barambah Creek’

H. divaricatus

H. heterophyllus (yellow)

NATIVE HIBISCUS AND HIBISCUS-LIKE
SPECIES AND HYBRIDS

By: Colleen Keena, Australia

The species of hibiscus that occur in Australia range from plants found only in Australia, such as Hibiscus splendens, H. divaricatus and H. heterophyllus, to plants with a widespread distribution, e.g. Hibiscus diversifolius and Hibiscus tiliaceus, now Talipariti tiliaceum. H. trionum has forms such as var vesicarius that occur only in Australia. Plants can be small like H. trionum and H. sturtii, through to large shrubs such as H. heterophyllus, H. divaricatus and H. splendens. Many are useful plants. The petals of Hibiscus heterophyllus, or of crosses from it, can be made into a delicious jam, cordial or syrup. Seeds of Hibiscus heterophyllus were collected on the Baudin expedition of 1800 and grown by Empress Josephine at Malmaison. The botanist Aim è Bonland wrote of its medicinal qualities, noting that it tasted like sorrel and could be grown in a vegetable garden. It was painted for the Empress Josephine by P.J.Redouté. This botantical painting can be seen in “Napoleon, the Empress and the Artist” by Jill, Duchess of Hamilton.

Volume 3, Number 4               Hibiscus International                   August-October 2003

Hibiscus insularis

H. trionum var vesicarius

H. sturtii

(All Photos In Photo Gallery:
Colleen Keena © 2002)

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Volume 3, Number 4               Hibiscus International                   August-October 2003

HIBISCUS HYBRIDIZING GUIDE GLOSSARY OF TERMS ALLELE – One of a pair of genes responsible for contrasting traits. ABSCISSING – With reference to the Hibiscus ovary or capsule, the separating and falling away from its point of attachment because of disintegration of the abscission layer. ANDROECIUM – The male element consisting of stamens and filament. ANTHER – The pollen-bearing part of the stamen borne at the top of the filament. ANTHER SAC – A sac-like unit of the anther containing the pollen. There are two pollen sacs in each lobe or half of the anther. ANGIOSPERM – A flowering plant that has its seed enclosed in an ovary. ANTIPODALS – Three nuclei found in the embryo sac at the end farthest away from the microphyle. AUTOPOLYPLOID – Polyploid, with all of the three or more basic chromosome sets derived from the same species. AUXIN – A plant hormone that regulates growth. CHIASMA – The ‘crossing-over’ point between chromosomes. During the production of sex cells, such as sperm and eggs, these crossing-over points are the places where sections of maternal and paternal chromosomes are swapped. At the chiasmata (pl.) the chromosomes are cut, ends are swapped and new hybrid chromosomes rejoin. This makes new combinations of pre-existing genes in the offspring produced by sexual reproduction. CHROMOSOME – A microscopic body made up of protein and gene-carrying D.N.A. Chromosomes exist as pairs in the nucleus – one chromosome in a pair coming from each parent. Hibiscus species have a set number of chromosomes. The organization of a chromosome enables it genes to be copied before mitosis so that each daughter cell receives a complete set. CHARACTERISTIC OR TRAIT – A specific aspect in the organization of an organism. Traits under genetic control such as petal color in Hibiscus may be inherited and are subject to natural selection. CAPSULE – In Hibiscus, a dry dehiscent fruit composed of five united carpels. DEHISCENCE – The method or process of opening of a seed capsule or anther. DICOLTYLEDON – A flowering plant such as Hibiscus whose seeds have two seed leaves or cotyledons. Hibiscus retain these seed leaves for a considerable period after germination.   DAUGHTER CELLS – Newly-formed cells resulting from the division of a previously existing cell called a ‘mother cell’. The two daughter cells receive identical nuclear materials. DIPLOID – Having two genomes or basic sets of chromosome. The genome is the total gene set possessed by an individual organism.

Volume 3, Number 4               Hibiscus International                   August-October 2003

DNA – (Deoxyribonucleic acid) is the long super molecule consisting of alternating units of nucleotides composed of deooxytribose sugar, phosphates and nitrogen bases. The complete sequence of bases, organized into triplets, is the genetic code. DOMINANT GENE – Principle first observed by Mendel that one gene may prevent the expression‎ of al allele or so-called recessive gene when they are present together at the same points on each of a pair of chromosomes. EMBRYO SAC – The tissue in a plant ovule that contains the egg, the antipodals, the polar nuclei and the synergids. EPICOTYL – In a seed,  the part of the embryo plant that lies above the attachment of the cotyledons and from which the stem and leaves will develop. EVOLUTION – The slow process of change by which organisms have acquired their distinguishing characteristics. FERTILIZATION – The union of two gametes resulting in the formation of a new individual cell (zygote). FILAMENT – A stalk of a stamen bearing the anther at its tip. GAMETE – A male or female reproductive cell that is capable of uniting with another gamete to produce a fertilized egg or zygote that, in turn, is capable of developing into a new individual. The gamete will normally have a haploid (halved) chromosome set. GENE – The functional section of DNA in a cell’s nucleus. A gene contains the information to specify the structure of a single protein. Genes are inheritable and are passed down from generation to generation. GENERATIVE NUCLEUS – The nucleus in the pollen grain that divides to form two sperm nuclei. GENETIC CODE – The sequential arrangement of the bases in the DNA molecule which controls traits of an organism. The code of all living things is concerned with protein construction. GENETICS – The study of genes and the part they play in inheritance. GENOME – The total gene set possessed by an individual organism. GENOTYPE – The hereditary constitution of an individual organization. HAPLOID – A term for the halved set of chromosomes found in sex cells. At fertilization the two halved sets reconstitute the species’ paired or diploid number of chromosomes. HEREDITY – The transmission of traits or characteristics from one generation to the next. HYBRID – A plant resulting from a cross between parents that are genetically unlike. The offspring of two different species or their infraspecific units. HYBRIDIZATION – (or outbreeding) the crossing of closely related strains of plants (or animals) to preserve certain genetic traits. INBREEDING – The process of a continual sequence of crossing between the offspring of a small, often isolated group of organism. Inbreeding generally results in an increase in the genetic similarity between individuals in the group since no new genes are produced.

Volume 3, Number 4               Hibiscus International                   August-October 2003

INCOMPLETE DOMINANCE – A blend of two traits resulting from a cross of these characteristics. MAGASPORE MOTHER CELLS – Diploid cells in the plant ovary that divides twice forming four haploid megaspores. MEGASPORES – Four cells formed from the megaspore mother cell, three of which disintegrate leaving one to develop into an embryo sac. MEIOSIS –  the particular type of chromosomal division that takes place during the production of sex cells or haploid gametes. In meiotic divisions diploid cells are transformed into haploid cells and new gene combinations are produced on single chromosomes by chiasma formation – the crossing over between chromosome segments. MICROPYLE – The opening in the ovule wall through which the pollen tube enters. MOTHER CELL – A cell that has undergone growth and is ready to divide. MULTIPLE ALLELES – One or two or more pairs of genes that act together to produce a specific trait. MUTATION – A change in genetic makeup resulting in new characteristics that can be inherited. Mutations can be caused by external influences such as toxic chemicals or ionizing radiation. They can also result from mistakes made during the copying of DNA. NATURAL SELECTION – The key evolutionary process whereby some natural variants of a species are favored because of their high levels of reproductive success. If the characteristics are inheritable the genes that determine them will increase in the population. NUCLEUS –  The part of the cell that contains chromosomes. OOGENESIS – The process of the development of female reproductive cells whereby the diploid chromosome number is reduced to the haploid. OVARY – The basal ovule bearing part of the pistil. OVULE – The structure that, after fertilization, becomes the seed; the egg containing unit  of the ovary. PHENOTYPE – The actual physical constitution of an organism; the outward appearance partly generated by its genes (its genotype) during development and physical factors such as environmental changes. PETAL – A unit of the corolla, one of the colored parts of the flower. PISTIL – The part of the flower composed of ovary, style and stigma. POLAR NUCLEI – The two nuclei in the embryo sac in flowers that fuse with one of the sperm nuclei to form the endosperm nucleus. POLLEN – The spores or grains borne by the anther of a spermatophyte. POLLEN SACS – Structures in the anther containing pollen grains. POLLEN TUBE – The tube formed by a pollen grain when it grows down the style of a pistil.

Volume 3, Number 4               Hibiscus International                   August-October 2003

POLLINATION – Transfer of pollen from an anther to a receptive stigma pad. PLOIDY – Chromosomes through which heredity is transmitted by way of genes occurring within the nucleus of each living cell of the plant body in sets which are known technically as genomes. Ploidy refers to the degree of duplication of genomes of or individual chromosomes making up the genome. Normally, each vegetative cell of the plant body contains two genomes and the plant is known as a diploid. Continued duplication of genomes leads to the formation of polyploid plants: four (tetraploid); five (pentaploid); six (hexaploid), etc. If the genomes included in the polyploid are duplicates of each other, that is, derived from the same individual or the same species, the plant is an autopolyploid. If the genomes are dissimilar, derived from parents belonging to different species, the plant is an allopolyploid. Many hybrid hibiscus are probably allopolyploid  POLYPLOIDY – The condition in which cells contain more than twice the haploid number of chromosomes. RECESSIVE GENE – A gene which has little effect on the phenotype of a plant when it is paired up with a corresponding dominant gene. REDUCTION DIVISION – The reduction of chromosomes during meiosis from the diploid number to the haploid number. SEXUAL REPRODUCTION – The process in which male and female sex cells or gametes fuse to produce the first cell of a new organism. SEED – A complete embryo plant surrounded by an endosperm and protected by a seed coat. SPECIES – The species is the primary or fundamental concept in the understanding of the forms of life. It is the basic unit in classification. Species are combined into genera and variations or subordinate forms of these may be distinguished as subspecies, variety and form in descending order of the botanical hierarchy. SPERMATOGENESIS – The process of the development of male reproductive cells whereby the diploid chromosome number is reduced to the haploid. SPERMATOPHYTE – A seed producing plant such as Hibiscus. STAMEN – The male reproductive part of the flower bearing an anther at its tip. STIGMA – The part of the pistil that receives the pollen grains. STYLE – The stalk of the pistil. SYNERGID – One of two structures formed on either side of the egg in the embryo sac of flowers. TETRAD – A group of four pollen grains or spores. TERTRAPLOID – A term used to indicate that a cell has four sets of homologous chromosomes. TUBE NUCLEUS – One of three nuclei present in a pollen tube. ZYGOTE – A fusion body formed when two gametes unite to become a diploid cell. As the zygote divides by mitosis so a new individual grows.

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Volume 3, Number 4             SPECIAL SUPPLEMENT                 August-October 2003

This article has been compiled by Colleen Keena from Queensland, Australia, Kristin Yanker-Hansen from California, USA and Marcos Capelini from São Paulo, Brazil and is part of the Marvellous Mallows series. 

PART 1
INTRODUCTION

Many times in novels or in films the hibiscus flower is referred to as fragrant. Yet in reality very few have that trait, except for the white hibiscus species from Hawaii.

Hawaii has a number of species of the Hibiscus family. Although some of these also occur in other countries and may have been introduced to Hawaii (P1;W1), there are a number of species of hibiscus which are endemic to Hawaii (W2).

Note: The "P" and "W" links in the text refer respectively to the printed  material ("P") and material on the web ("W") listed in the "References"  section below.

One of the species endemic to Hawaii is Hibiscus arnottianus. It is noted for its fragrance (W3). It is described as a spectacular shrub during its flowering season with its large, white flowers. While the frag-rance and beauty of Hibis-cus arnottianus are impor-tant features, it is often used by horticulturists to hybridise with Hibiscus rosa-sinensis (W4)–[H. arnottianus Bush In Australia: Richard Johnson © 2002].

Therefore, while Hibis-cus arnottianus is a beauti-ful plant in its own right, with fragrance and spec-tacular flowering,its com-patibility with Hibiscus rosa-sinensis is a feature that has not only been of interest to early hybridisers but continues to attract those interested in developing new forms of hibiscus. This interest in hybridising was reflected in the very first issue of Hibiscus International by Jill Coryell (W5) and will be discussed in Part 4 of this article.

THE SPECIES

Hibiscus arnottianus is an evergreen multi-trunked shrub or small tree, growing to 8 - 10 m (24–30 ft) high, with a dense crown of foliage and smooth trunk and branches. The leathery, dark green, ovate leaves are entire (with smooth margins) and are 5 – 15 cm (2–6 inches) long. The leaf veins and stems commonly are red. The tubular, slightly fragrant, solitary flowers, measuring up to 4 inches across, are white with pinkish veins or pure white with red filaments and a magenta staminal column. The papery fruiting capsule is about 2.5 cm (1 inch). It contains seeds covered with fine yellowish-brown hairs (tomentose) (Upper right photo: H. Arnottianus Bush in Australia: Colleen Keena © 2003).

Volume 3, Number 4               Hibiscus International                   August-October 2003

Three subspecies of Hibiscus arnottianus are currently recognized (1997:W6):

subsp. Arnottianus – has smooth young stems, leaves, pedicels, and calyces; native to Oahu (Wahiawa to Niu Valley).

subsp. Immaculatus – has unusually deeply crenate leaves and a white staminal column; native to Molokai (Wailau, Waihanau. and Papalaua valleys).

subsp. Punaluuensis – a robust form with moderately coarse pubescence on young stems, leaves, pedicels, and calyces; native to Oahu (Kaipapau to Waiahole).

Cultivars have been selected by the Harold L. Lyon Arboretum: 'Kanani Kea' a selection with large flowers and good form. 'Shy Girl'-flowers with a pink blush on the back of the petals and edges (W6).

One of the subspecies, Hibiscus arnottianus subsp. immaculatus was design-nated as endangered in 1992 (W7).

The flower buds of Hibiscus arnottianus subsp. immaculatus were eaten, or are eaten still, by Hawaiians as a gentle laxative. Cordage was also made from the stripped bark (W8). A more detailed description of the species and subspecies is available (W9).

PART 2
CULTURE

INTRODUCTION
Hibiscus arnottianus is now grown well beyond Hawaii. For example, it is grown in areas as far apart as California and Queensland, Australia, and in a range of conditions. Any consideration of culture needs to take into account the environment in which Hibiscus arnottianus occurs. Hibiscus arnottianus is found in dry to wet forest areas at 300 m - 800 m (1000-2500 ft) elevation. It grows best under filtered shade in moist, well drained soils, but it will tolerate full sun (W10). Although this plant will thrive in partially shaded areas, for at least the subspecies immaculatus, it will bloom more in full sun (W8) (Left photo: Colleen Keena © 2002).

Volume 3, Number 4               Hibiscus International                   August-October 2003

CULTIVATION
Although in its original location Hibiscus arnottianus grows best under filtered shade, references on cultivation recommend a full sun position (W:10) with the ideal being an open sunny situation (P3).

Experience with growing it in California and Queensland sug-gests that established plants can recover from light frosts (-4C/25 F) but if planting it in an area where frosts are likely, growing in a pot so it can be sheltered in winter is recommended.

As already noted, Hibiscus arnottianus occurs in well drained soils. References relating to cul-tivation indicate that it grows best in rich sandy soil (P3) or an organically rich, well drained soil (W8) (Upper right photo: Richard Johnson © 2002). Although it will ultimately become a small to medium size tree, it is a slow grower and will remain a shrub for many years (W3). It is long-lived, hardy and resistant to root-rot and borer (P3).

Volume 3, Number 4               Hibiscus International                   August-October 2003

WATER REQUIREMENTS
Although occurring naturally where there are moist well-drained soils, Hibiscus arnottianus will tolerate dry con-ditions (W10). Its water requirements are described as moderate (W3) although liberal water and fertiliser should be ap-plied during the flowering season, which is summer and autumn (P3).

LANDSCAPE USES
Hibiscus arnottianus may be used as a single specimen plant, in groups for mass plantings, or as a screen or hedge plant. Its medium-textured foliage and flowers make it attractive for landscape uses (W10). It can also be planted as an accent in front of dark backgrounds such as a rock wall to show off its beautiful white flowers (W8). It can be grown as a large container plant (W10). When grown in a container, it can be positioned to enjoy the fragrance (Upper left photo, in Tahiti: Richard Johnson © 2002.

PRUNING
The two-day blooms are produced freely on short spurs from older wood and so it is best left unpruned. However, a severe pruning, about halfway, in spring every four to five years is recommended to keep the plant healthy and in a good shape (P3).

PESTS
It has no significant insect pests or diseases although Chinese rose beetles and white flies may cause minor damage (W3). There may also be some problems with thrips, and aphids. Stink bugs may cause bud drop (W10). In the sub-tropical areas of Australia, scale and mealy bug may be a pest.

Volume 3, Number 4               Hibiscus International                   August-October 2003

CARE AND MAINTENANCE
No special care is required (W10). (Right Photo: Close-up of staminal column of H. arnottianus - Geoff Keena © 2002).

PROPAGATION
Rooting terminal cuttings is recommended (W3) although either terminal or stem cuttings can be rooted with rooting hormones under mist (W10). Hardwood cuttings, pencil thickness, devoid of leaves, 12 - 16 cm (5 - 6 inches) long, taken in spring and placed in coarse river sand and peat, strike readily (P3).

As the plant sets seed readily, it may be grown from seed sown in the spring (P3). However, seedlings may not be true to type (W10). Seedlings are slow-growing (W3).

Hibiscus arnottianus also can be propagated by air-layering or grafting onto other Hibiscus species (W3; W10). 

PART 3
HYBRIDISING

As was noted in the introduction, there was an article on hybridising hibiscus in the first issue of Hibiscus International. The author wrote that although hibiscus hybridising was tried at earlier times and in other places, Hawai'i was in fact the place where any large scale hybridizing took place, and the first recording of this was in the mid 1800s. She continued that large scale interest took off around the turn of the century, and by 1911 there was a Hawaiian Hibiscus Society, with several thousand hybrids displayed at the first show. Native Hawaiian hibiscus such as H. kokio (koki'o 'ula'ula) and several varieties of native Hawaiian whites (Koki'o ke'oke'o) were often used as parents, crossing with plants introduced from other places (W5).

Many variants of Hibiscus arnottianus have been or are in cultivation, and some have been hybridized with Hibiscus rosa-sinensis (Wilcox & Holt, 1913; Bates, 1965 in W9).

Volume 3, Number 4               Hibiscus International                   August-October 2003

The reason the native Hawaiian white hibiscus could be used in hybridising is that Hibiscus arnottianus is one of the species which is genetically compatible with Hibiscus rosa-sinensis (P4).

Note: Not only is Hibiscus arnottianus compatible in crossing with  Hibiscus  rosa-sinensis to produce horticultural cultivars, but it can  also be used as an  understock when grafting the hybrids. As a  rootstock it is long-lived, hardy  and resistant to root-rot and borer  (P3).

In relation to the varieties of native Hawaiian white hibiscus, hybridising records can be confusing. Early records may have used common names, e.g. 'Ornamental Hibiscus in Hawaii' of 1913, (W11). This reference states that Hibiscus arnottianus is a native white species which occurs under several quite distinct forms, at least from the horticulturists standpoint. These forms are commonly called Tantalus White, Waianae White, Punaluu White and Nuua-nu White.

The text notes that Hibiscus waimeae*(W11) is also a native species with pure white flowers, and occurs under at least three forms, referred to as Knudsen White, Rice White and Lydgate White. It continues that Molokai White is apparently an undescribed species. There is also a description of a cross between Knudsen White and Punaluu White, that is, is a cross between Hibiscus waimeae and Hibiscus arnottianus. Crosses between the two native white species are a further complication.

Another source of confusion, such as in the International HIBISCUS rosa-sinensis Register and Checklist (W12), arises from the fact that not only might common names, rather than botanical names have been used in the records, but subspecies may not be shown. Common names include Punaluu White, Nuuanu White and Tantalus White. Botanical names are given as Hibiscus arnottianus, Hibiscus immaculatus and Hibiscus punaluuensis.

In the Hibiscus Register (W12), common names given in the records include Tantalus White (Albo Lacinatus), Punaluu White (Ross Estey), Waianae White (Annie Hobron). Botanical names include Hibiscus arnottianus (Agnes Galt), Hibiscus immaculatus (Mrs James E. Hendry) and Hibiscus punaluuen-sis (numbered seedling).

Volume 3, Number 4               Hibiscus International                   August-October 2003

       

Crosses in the Bulletin (W11) and in the Hibiscus Register (W12) where Hibiscus arnottianus was a parent, indicate that seedlings range in colour from nearly white, to pale pink, light crimson pink, to pink suffused with apricot to yellow.

Hibiscus arnottianus has a number of features of interest to hybridisers. Firstly, it sets seed readily (P3). It is interesting that most of the crosses shown in the Hibiscus Register list Hibiscus arnottianus as the pod parent (W12). The exception to this is Punaluu White which is shown as the pollen parent of five crosses, including Ross Estey (W12). Secondly, the blooms last two days. The third feature is that the flowers have an exquisite fragrance (P3). This characteristic is pos-sibly of most interest to current hybridizing prog-rammes.

One of the people involved in using Hibiscus arnottianus in a planned hybridizing programme is Brian Kerr who lives in southeast Queensland, Australia. The gardening conditions where Brian lives are described as sub-tropical.

Volume 3, Number 4               Hibiscus International                   August-October 2003

PART 4
   

Hibiscus arnottianus is described as having flowers which are weakly fragrant (W9) whereas the flowers of Hibiscus waimeae are described as strongly fragrant (W9). Hibiscus waimeae can be divided into 2 subspecies: subsp. hannerae and subsp. waimeae (W9).

I have most interest in Hibiscus waimeae, especially Hibiscus waimeae subsp. hannerae as I have read about the 'pervading odour' of Hibiscus waimeae. For now I will work with Hibiscus arnotiannus.

I agree that there is much confusion. What is a true Hibiscus arnotiannus? What we have in southeast Queensland as Hibiscus arnotiannus may be a hybrid between some of the native Hawaian types. Hibiscus arnottianus as I know it just does not match with the descriptions I have read of this species or its subspecies.

My experiences so far are that Hibiscus arnottianus (hereinafter referred to as "A") is well suited to growing in full sun, enjoys a yearly prune and will remain a dense shrub with this treatment. Its growth speed is quite good. For grafting purposes, it can be used as understock and itself has taken on Albo Lacinatus (hereinafter referred to as "AL"), Landersii and some of my discarded seedlings. Cuttings will root easily, but are slow to get going at my place.

The blooming capacity of Hibiscus arnottianus is amazing, with hundreds of blooms on a 1.5m bush. It does not seem to need a great deal of attention and can grow well in a variety of soils, the best results coming from sandy soils, high in mineral matter. Blooms last one day only in hot weather and two days in the cooler weather. The hibiscus beetle loves this white-coloured bloom of course. It is not resistant to Erinose mite.

Volume 3, Number 4               Hibiscus International                   August-October 2003

Hibiscus arnottianus does not self seed readily under Sunshine Coast conditions, though I do get the occasional small pod resulting in one or two seeds only. It will set seed readily when hand pollinated and produces large, full pods averaging perhaps a dozen seeds. The highest number of seeds were achieved when using Hibiscus schizopetalus (hereinafter referred to as "S").

I have used Hibiscus arnottianus with a variety of today's coloured blooms to give myself a varied base of colours to use in future breeding. The main aim here is to put the blooming capacity and self rooting ability of Hibiscus arnottianus into new cultivars resulting from this cross. I think it is a good idea to cross back to older varieties every few generations.

My interest in inter-crossing the older varieties and species started as one of general interest, but is now a search for knowledge, a search to try and find, prove and confirm‎ the parentage of some of the older varieties and to produce a frilly edged, mini white. Perfume would be a bonus. Also, by back-crossing with modern day blooms in a variety of colours and then inter-crossing these, to try and produce some frilly edged, yellows, purples, browns and multi-colours on attractive, perhaps caney, bushes. Hibiscus arnottianus does fit in to this programme with its contribution as the best bloomer, white colour and perfumed background. As far as perfume is concerned, I cannot detect much odour from Hibiscus arnottianus. The only perfumed hibiscus at my place is my Hibiscus arnottianus (A) X Albo Lacinatus (AL) seedling.

The following are the crosses so far using the following pollen parents:
1. A x (Purple Robe x Hibiscus schizopetalus)
2. A x (Shirley Howie x Alex Pimm -1)
3. A x (Shirley Howie x Alex Pimm -2)
4. A x Leopard

   

Volume 3, Number 4               Hibiscus International                   August-October 2003

5. A (x) AL: has produced very tall A look-a-likes in all but one. This was the slightly, frilly-edged mini with a flowery perfume that I posted to the IHS List.

H. arnottianus (x) Albo Lacinatus
Brian Kerr © 2003

6. A (x) S: with all blooms being near exact replicas of AL in habit and bloom colour. The most interesting of these is one with speckles evident, like you see in Patricia Noble (Sport of Ross Estey - this having A in its background). These speckles are not unlike Ali Uii speckles in some way, though not as 'standoutish' as they are on a pale bloom and not as wide-spread. Leaf colour, shape and bush habit is noticeably different to me, but not to other observers. It appears that these speckles do not come through in photography.

     

Volume 3, Number 4               Hibiscus International                   August-October 2003

7. A (x) Cuban Variety (CV): A deliberate cross to try to produce the ultimate bloomer in any colour that resulted, with maybe perfume as an afterthought; also to get a compact bush, as both produce compact bushes in my crosses so far.

8. A (x) (Cuban Variety x Albo Lacinatus) (CVAL-1): A deliberate cross to try and resurface the blooming capacity of A and the amazing blooming capacity of CV in any colour that resulted, with maybe perfume as an afterthought; also to get a compact bush. The result of this cross will be put to A (x) AL above, the white, mini, slightly perfumed, fringed single.

 

9. A (x) Herm Geller (HG): A x HG has not bloomed, but the bush needs men-tioning as it is so well formed. However, the leaf seems to suffer from a brown fungal type infection in winter on the top of the leaf. Initially the marks look appealing, but eventually the leaf dries and falls off, leaving a stark, unattractive bush.

10. A (x) Nasali Pink (NP): crossed these as NP (Right photo: Jim Purdie © 2002) is a great bloomer - to produce one with excellent blooming capacity and to get a compact bush., as both produce compact bushes in my crosses so far.

Volume 3, Number 4               Hibiscus International                   August-October 2003

All others are progressing in varying ways and if they survive the red spider and cold and wet (and a batch of bad, heavy potting mix), will hopefully bloom in the next year.

Post Script: Geoff Harvey has noted (personal communication) that  outside Hawaii, Hibiscus arnottianus was hardly ever known by its  species name. Hibiscus arnottianus has been and is still known as  'Wilder's White' in Australia (P3). 'Lillian Wilder', which is shown as  having 'Knudsen White' as its pod parent and H. waimeae as its pod  grandparent, has been incorrectly known as 'Apple Blossom' in  Australia  (W12).

REFERENCES: (Printed Material)

1. Sohmer, S.H. and Gustafson, R. (1987, 2000) Plants and Flowers of Hawai'i,      University of Hawaii Press, Hawaii.
2. Howie, J. (1980) Hibiscus Queen of the flowers. First Edition, Prestige Litho      Printing Co., Australia.
3. Beers, L. and Howie, J. (1985) Growing Hibiscus, Kangaroo Press Australia.
4. Gast, R. Chapter 2 in The Genetic History of Hibiscus rosa-sinensis in Beers,
     L. and Howie, J. (1985) Growing Hibiscus, Kangaroo Press Australia.

REFERENCES: (Web Links - as of 30 June 2003)

1.   http://www.hawaii.gov/health/oeqc/garden/eioegpic.htm
2.   http://www.botany.hawaii.edu/faculty/carr/hibiscus.htm
3.   http://www.hawaii.gov/health/oeqc/garden/eioegkeo.htm
4.   http://www.internationalhibiscussociety.org/hiv1n1.htm#_Hybridizing_
      In_Hawaii_3
6.   http://www.tropical-seeds.com/tech_forum/flowers_orns/oahu_wt_hibiscus.pdf
7.   https://ecos.fws.gov/species_profile/SpeciesProfile?spcode=Q2BC
8.   http://starbulletin.com/2003/01/03/features/garden.html
9.   http://www.hibiscus.org.au/part2.htm
10. http://www.tropical-seeds.com/tech_forum/flowers_orns/oahu_wt_hibiscus.pdf
11. http://www.hibiscus.org.au/hawaiian.htm
12. International HIBISCUS rosa-sinensis Register and Checklist, 2002 (CD) ICRA (Hibiscus)          Register/ChecklistWeb: http://www.geocities.com/auhibsoc/ira/register.htm

Volume 3, Number 4               Hibiscus International                   August-October 2003

* Although the text uses the spelling H. weimeae, this spelling is not included in the  International Plant Names Index http://www.ipni.org

The authors wish to thank Brian Kerr for his assistance with this article. Thanks also to Chris Noble for his help.

The next Hisbiscus International No. 17 promises to be an even more colorful and balanced issue. Geoff Harvey’s article on Hibiscus Hybridization continues with Part 3 – Applied Genetics, which presents interesting observations on breeding by mass selection; line breeding; mutations; and, selecting compatible varieties for hybridizing, among others. Gloria White has compiled another very nice piece on Ed and Jane Flory from Florida,USA H.I.17 also introduces a new section called “From The Archives”, which is a selection of articles written in the past by some well-known luminaries in the World of Hibiscus. As with the previous issue of H.I., we have another interesting I.M.H.O. feature written by Allan Little from Glasshouse Mountains, Australia – on the topic of hybridizing. Allan shares his experiences and observations, this coming from a man recently judged as the “Hybridizer of the Year” in Australia. There are also other articles of interest that will be covered in this next issue for our growing number of members. We are also proud to present an excellent compilation of some hibiscus cultivars from Europe in the Photo Gallery Section of H.I.17 thanks largely to the efforts of Madame Francoise Levavasseur of Southern France who provided most of the photos (From The Editor).

Board of Directors 

President:  Jim Purdie – Brisbane QLD, Australia
Past President: Richard Johnson – Tamanu, Tahiti, French Polynesia
Vice-President: Carlos C. Quirino, Jr. – Metro Manila, Philippines
Secretary/Treasurer: Richard Mansbridge – Australia
American Rep: Robert Cook – Kansas, USA
Australian Rep: Graham Boytell – Brisbane QLD, Australia
European Rep: Jean-Francois Giraud – Isere Valley, France
Asian Rep: Carlos C. Quirino Jr.
India Rep: Francy Kakkassery – Kerala, India
Pacific Rep: Richard Johnson
Webmaster: Joseph Dimino – Sicily Italy 

All Rights Reserved © 2003
   
Articles for use in this publication should be submitted by e-mail
to the Editor at: swanwing@skyinet.net

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