The aim of breeding always has been to produce plants and animals better suited to human needs. Until recent times no one had any clear idea of even the most basic laws of heredity. The development of an improved breed was mainly a matter of chance. Many of our top Hibiscus hybridizers started out with very little knowledge and as their hobby grew they acquired experience and understanding. The modern knowledge of the laws of heredity has made breeding much more efficient, still our hobby remains anything but an exact science. Hundreds of different traits may be involved in a breeding experiment, thus the results are usually impossible to predict.

Plant Breeding By Mass Selection

In mass selection, a very few parent plants are chosen for breeding from a great number of individuals. From all the plants grown from seed we may be lucky to be able to choose that one plant that has the traits that we want. Mass selection is probably the oldest form of plant breeding with farmers saving the seeds from their best plants for the next planting. In this way, the offspring are most likely to have the desired traits. Perhaps the Polynesians when departing for their great unknown adventure into the vast Pacific Ocean selected seed from that particular Hibiscus that best suited their needs.

Hybridizing is the crossing of two different, but closely related strains or sometimes species. The latter is referred to as an interspecies cross. When the new hybrid plants results it is hoped that the hybrid strain will have the best traits of each parent. We might choose one parent because it grows quickly on its own roots into a compact well-branched bush. The other parent may be chosen for the fine quality of its blooms.

Often the new combination of genes in a hybrid brings out traits not shown in either parent. The hybrid may grow larger than either parent or bloom more profusely. It may be suited to a wider range of climates and resist pests and diseases. These improvements are known examples of hybrid vigor.

Inbreeding or Line-Breeding

This is the opposite of hybridization. Suppose that we have developed the type of plant that we want either by mass selection or hybridization. The next step would be to grow more plants with the same traits. Inbreeding involves self-pollination of a single parent and in this way no new genes are introduced from a different plant. With each generation of self-pollination we select those plants with the traits that we desire. We may decide to backcross in order to fix a given trait from one of the ancestors or to continue on until the strain becomes genetically pure. I doubt if Hibiscus hobby breeders would consider long programs of line breeding as it could take 10 years or more to acquire pure strains. The variety that we call 'Bruceii' in Australia with its bright yellow flowers and usually masses of seed from self-pollination is close to a pure natural strain in that the seedlings are all nearly identical to the parent in type of bush and flower. With Hibiscus generally, that may have been crossed by humans for nearly two hundred years, will carry genes from many different strains, forms and species from all over the Indo-Pacific region.

Mutations

The pink tea rose is an example of a somatic or bud mutant. It developed when a color gene mutated in a stem cell of the white tea rose plant. All of the cells of the branch that developed had the mutant trait.

With Hibiscus many strains have resulted from bud mutation. Mutations can also be caused by external influences, such as toxic chemicals or ionizing radiation. This is beyond the likely consideration of a hobby plant breeder due partly to the cost factor and dangers involved.

Most mutations in the functional part of genes will produce mutant, altered versions of the proteins for which these genes are coding. These altered proteins lead to adaptations and changes in characteristics that may or may not enhance the fitness of an organism. 'Color genes' that mutate seem to be an inherited trait in some instances e.g., 'Dorothy Brady'.

The Color Of Hibiscus

Bloom color is determined by a group of genes. Some of these are "structured" genes which are directly concerned with producing color i.e., genes for the intensity of red, yellow and purple. Others are control genes that switch the activities of other genes on and off. In white flowers no color pigment is produced (as in Byron Metts [Great White (x) Cherry Blossom] (left photo, inset). The first control gene is not active so none of the color genes operate.

If we crossed a genetically pure red Hibiscus with a genetically pure white, probably all the seedlings would be identical pink. Reference to Gregor Mendel's breeding experiments explains positive and recessive genes and the two-gene aspect of inheritance in operation.

When we examine the complicated multi-colored blooms resulting from some modern hybrids one can wonder at the large number or group of genes involved in the determination of color. With Hibiscus, pink is the most dominant color whilst pure white is rarely encountered in seedlings. Backcrossing onto Hawaiian whites would allow a pairing of some recessive white genes..

Bloom Colors And Breeding

The aim of many Hibiscus hybridizers has been to produce a true blue hibiscus flower. As the primary colors yellow, blue and red are unobtainable by mixing other colors, the plant breeder will be hard put to progress beyond the indigo violet end of the spectrum.

It is suggested that readers refer to the very good article by Hans Drost in "The Hibiscus" publication Vol.3, March-April 1987 No.4. With so many thousands of hybrid Hibiscus x rosa-sinensis in existence it is possible that a mutation will eventually give us a gene for true blue. If genetic engineering were used to achieve this end, considerable harm to our hobby would eventuate.

The seven distinctive colors that can be conventionally distinguished in the spectrum are: red, orange, yellow, green, blue, indigo and violet. Visible to the human eye is the wavelength from 0.0006 to 0.00075 mm orange-red at one end of the scale and 0.0005 to 0.00038 mm indigo violet at the other end of the scale.

The main reason for bloom color is to achieve pollination by attracting the pollinators, be they bees, moths, birds, animals or whatever. Hibiscus blooms will be at their brilliant best when they first open so as to attract pollinators as soon as the pollen dehisces and the stigma pads are receptive. Normally they will deteriorate and wither as soon as the pollination process has been completed.

Selection Of Compatible Varieties For Hybridizing

Almost all Hibiscus varieties produce viable pollen so selection of male parents is not a problem. If species are to be used in the breeding program, they will be better suited as male or pollen parents. It is considered that female parents are much more difficult as only a small percentage of modern hybrids, due to their genetic complexity are reliable seed setters. Perseverance in pollinating will often result in a seed capsule, even after numerous unsuccessful attempts. If you want to make a cross don't give up. After many months under different weather conditions, that one capsule may eventually award your efforts. It is possible that a well fertilized actively growing plant will not set seed as readily as one under some stress from old age or poor nutrition. It is not known if soil ph has any bearing on seeding.

John Richardson's Article in the Hibiscus Digest Vol.11 Nov.-Dec. No.2, 1994 recommended female parents for breeding as follows: Charles Schmidt; Joyce A.; Topaz Glory; Secretariat; Miniskirt; Grey Lady; Crimson Ray; Honey Do; Gina Maria; and, Fiesta. The successful Australian hybridizers have used the following cultivars as female parents on multiple occasions to produce registered seedlings: Fiesta; Blueberry Tart; Elena Mia; Burgundy Blush; Shirley Howie; Topaz Glory; Surfrider; Lightning Ridge; Nathan Charles; All Aglow; and, Fire Engine.

From the nomenclature record, some of the leading Hibiscus varieties that have been used successfully as hybridizing parents to produce named cult-ivars are as follows:

 

Selection of female (pod) and pollen parents deserves a lot of thought and usually some test crosses to identify parents desirable to your program. From the above it can be seen that All Aglow potential has perhaps been exhausted and something new from the gene pool would be a better option.

 
 

 

 

Peter Troon has given me (part of) an extensive article on the history of the Hibiscus. It was published some years ago in AmHs' The Seedpod and was compiled by Ross Gast from the historical records of prominent botanists and his own research.

Ross H. Gast died in 1983 and was a man of many accomplishments: reporter, freelance writer, biographer, editor, publisher, farm adviser, managing director of a seed company, inventor (Twist'ems) are a few and he still maintained his deep interest in hibiscus, touring the world in search of the "lost" species. As one of the founders of the Amer-ican Hibiscus Society, he was greatly respected as a world authority on hibiscus. Although he bred many hibiscus, his best-known variety in Australia is Ross Estey (Ecstasy) - (Left Photo - Bob Rivers-Smith © 2002).

Most writers on botany, before Linnaeus created his classification methods, had too many "varieties" in each species but he tended to include species as varieties within species. In 1759, Philip Miller's "Gardener's Dictionary" commented on this confusion. Linnaeus chose his type plant, a double red form, calling it H. rosa-sinensis - Chinese Rose - although it is a native of India, not China. Botanists continued to group it and offer ornamental hibiscus under this misleading name. The resultant hybrids were included although their progenitors were native to such disparate parts of the world as the Islands of the Southern Ocean and Hawaii, as well as India. The plant is believed to have had wide distribution both eastward and westward from India during the Polynesian migrations in the Christian era.

 

The earliest pictorial representation of the double red which Linneaus called H. rosa sinensis appears in Van Rheede's "Hortus Malabarensis (1678). It had many names such as H. rosa-sinensis rubra plena, Schempariti, perhaps an Indian word, and also as rosa javanica, indicating that it was well established in the Dutch East Indies.

    It is described in the Gardener's Dictionary as:

" ... this sort grows naturally on the coast of Malabar (southwest coast of India); it rises with a woody stalk 12 or 14 feet high dividing into many branches near the top, garnished with oval-sawed leaves ending in acute points, lucid green above but pale on their undersides, placed without order. The flowers come out from the side of the branches at the wings of the leaves on pretty, long foot-stalks; they are composed of many oblong, roundish petals of red color which expand like a rose. The flower being as large when fully blown as the common red rose and as double."

In view of its historical background the question rises as to what modern hybridizers should call their cultivars. The known cross compatible species which are considered to have been progenitors of modern hibiscus hybrids include H. schizopetalus, native to East Africa; H. liliflorus, H. fragilis (Right photo, this page: (Courtesy of Jean-Francois Giraud) and H. Boryanus (Left photo on following page: (Courtesy of Richard Johnson © 2002) from the Mascarene Islands (e.g., Mauritius, Reunion and Rodriques) in the South Indian Ocean; the Ha-waiian whites, H. arnottianus and H. wai-meae; H. kokio, the Hawaiian red; H. stork-kii Seem; Fiji, and H. denisonii, origin un-known. Gast observes that H. storckii and H. denisonii may be synonymous and that the same is true of H. liliflorus and H. boryanus. Linnaeus' double red is also now considered a species.

 

The first single red to be pictorially represented in English horticultural literature appeared in Curtis Botanical Magazine in 1792. Forms of ornamental hibiscus other than the double and single red began to appear in English horticultural publications late in the 18th Century. During the years 1800-1810, John Reeves, an English tea merchant residing in China, began to collect plants and ornamental shrubs in Chinese gardens and sent herba-rium specimens to Kew Gardens, in London. During this time he also commissioned a Chinese artist to make watercolor paintings on rice paper of hibiscus. All of the hibiscus in his collection were double. These paint-ings were sent to the Royal Horticultural Society in London. They include a double orange called H. rosa Sinensis flava, a double buff referred to as H. rosa-sinensis lutea; a double red and white named H. rosa-sinensis variegata; and a double white, unnamed.

The origin of the doubles other than H. flora plena rubra shown in the Reeves collection raises the question as to whether they were hybrids, sports or true species. The variegated form could be a hybrid with the double red as one parent and H. schizopetalus as the other. The fact that there were trade relations between Southeast Asia and the African East Coast is well estab-lished. But whence came the double orange, double buff and the double white? They could have been true species no longer found in the wild or sports from H. flora plena rubra but this hardly seems possible as hibiscus do not sport easily. If they were hybrids, what were the parents? The fact that there were other true species existing at the time in Southeast Asia but lost to cultivation is one possible answer. However, the probability is that they are hybrids resulting from crosses between the double red and H. liliflorus.

The first recorded inter-specific hybridization of ornamental hibiscus was the work of Charles Telfair, of Mauritius, deep in the South Indian Ocean, during the years 1810-1827. He was, therefore, the precursor of the hundreds.

Continued In Part 2 of Hibiscus International No.17

 

 

 

 

 

 

Ileana Frometa Grillo was born and raised in Caracas, Venezuela. She began her art studies at the Fine Arts Museum in Caracas, specializing in charcoal drawing, portraiture and oil pastels. She moved to California in 1980, where she studied 4 years in the art program at Cal State University at San Bernardino followed by two years of black and white photography study with Andrew Shumaker at the University of Redlands. Her artwork contains imagery and symbolism culled from her Caribbean and South American roots and combines a traditional style with modern elements. She has exhibited and sold her pieces in Venezuela, Hawaii and California and was awarded a Finalist position in the MacWorld Expo 2000 Digital Art Contest.

 


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