by Elizabeth Shaheen
There is great controversy as to the genetic history and origin of the ornamental Hibiscus rosa-sinensis. The literature on Hibiscus rosa-sinensis does not establish its geographical origin, however, most early references claim it a native of China and its name rosa-sinensis means Chinese rose. Many pieces of the puzzle are missing and the complete picture may never be revealed. This is compounded by the fact that Hibiscus rosa-sinensis has not been found in the wild.
When referring to ornamental hibiscus as Hibiscus rosa-sinensis, modern taxonomists cite as their authority Carolus Linnaeus’s Species Plantarum (1753).
It is thought that the form he referred to was in all likelihood the double-red, which had a wide distribution throughout China, India, Southeast Asia and the Pacific Islands in pre-European exploration days.
In later years, a single red form was included in the taxonomic analysis of this hibiscus.
The early years of the 19th century witnessed the introduction of other forms of hibiscus into the greenhouses of Europe that carried the same name H rosa-sinensis.
Many of these had travelled from Asia and the islands of the South Indian Ocean where they were thought to have been cultivated before recorded history.
Others were man-made cultivars from inter-specific crosses in a number of the world’s regions.
Illustrations of a double red hibiscus date to 1678 and in 1731 Phillip Miller, curator of London’s Chelsea Physic Garden, introduced a double-red form and others to England.
In 1810, English tea trader and a Royal Horticultural Society member, John Reeves commissioned a Chinese watercolour artist to paint various hibiscus cultivars he had seen growing in China, forms which he and other enthusiasts sent to England for propagation.
Housed in the Lindley Library of the society, these illustrations include double forms of red, pink, buff, orange, yellow and white hibiscus.
Hibiscus became an in-vogue stove-plant in the 19th century, lovingly nurtured in the kitchens of the period.
The passionate plant lover Charles Telfair was greatly responsible for the advancement of ornamental hibiscus from his home on Mauritius, one of the Mascarene group.
In 1820, he began crossing the native H liliiflorus with old forms of H rosa-sinensis which had been introduced to the island.
The renowned plants-man, Robert Barclay, of Bury Hill, Surrey, was the happy recipient of Telfair’s hybrids who in turn passed them to English gardeners.
A momentous period occurred around 1900 when Hawaii, Ceylon, India, Fiji and Florida embarked on bringing together hibiscus species and hybrids and is the nucleus of today’s principal interest.
Owing to this work, it is now held that the ornamental named Hibiscus rosa-sinensis is not a species but a decidedly polymorphic group composed of complex hybrids and their offspring.
This has led some taxonomists to believe that due to its hybrid character that in order to represent it correctly it should now be referred to as Hibiscus x rosa-sinensis.
This topic will no doubt continue to be heartily discussed among the learned Hibiscus rosa-sinensis hybridisers.
The peoples of Malaysia, Fiji, Tahiti and Hawaii have embraced Hibiscus rosa-sinensis into their cultural and religious traditions, but it was in Hawaii in the beginning of the 20th century that the breeding of H rosa-sinensis really dominated.
The native forms, which were in reality imported from China and introduced by the Polynesians, were crossed with pure native Hawaiian hibiscus and with, predominantly, the split-petal, H schizopetalus, known as the Japanese lantern for its flower form.
The consequent offspring were dramatic and impelled fervent progress in developing ever-more wonderful blooms.
In 1923, the Territory of Hawaii adopted the hibiscus as its State flower. It is also the national flower of Malaysia where it is known as Bunga Raya.
The flowering plants we marvel at and cultivate today are the product of hybridisation efforts by many hybridisers over the course of several centuries in widely disparate regions of the world.
The last decade has enjoyed, new and exciting breeding techniques aimed at producing stronger, compact and ever-more floriferous garden shrubs.
A vexing problem remains. Although thousands of hibiscus rosa-sinensis cultivars’ nomenclatures have been recorded, it is estimated that two-thirds of named cultivars have been lost to future generations and us.
Because only a few people grow many of the named hybrids, they ultimately vanish if no one propagates them.
In spite of this, there are over 6,000 names registered, which still leaves us spoilt for choice!
Because many cultivars want for strong roots or a sturdy vertical habit, grafting is carried out on to cultivars with good, sound root systems.
Shrubs displaying insufficient branching, scanty foliage or a drooping habit are to some gardeners, not garden worthy.
If you have such a plant, try improving its performance by training it as a standard or espaliered against a west-facing wall.
Besides being a popular garden plant, for Bahrain’s gardens, it has its place also as an ornamental plant in pots, in a small garden and as a houseplant.
A novel way to grow one is as a standard with several other varieties grafted on to it. This form will attract a lot of attention and provide an exciting topic of conversation.
Although most H rosa-sinensis flower’s last for only a day, as one fades another bud is standing by to open.
Many of the Hawaiian hybrid’s magnificent large blooms will last for two days, sometimes three.
The beauty of these plants is that they flower much of the year in Bahrain’s gardens. Ours, mostly, take time-out to rest during the relatively short winter months.
Hibiscus, as well as its ornamental value, has numerous other uses, which includes medicinal and cosmetics for dyeing the hair and eyebrows. Juice extracted from the flower provides a shoe polish: that’s why it’s known as the shoe flower.
Although we enjoy many beautiful hybrids of rosa-sinensis in our garden, if asked to name a favourite then I should have to say that it is ‘The Path’.
This comeliness has sunset shades of dramatically ruffled and tufted flowers to seven inches (17.5cm) across, having bright sun-yellow edged petals with luminous-pink centres.
It has a bushy, upright habit and grows to around six to eight feet (1.8-2.4m) tall with a spread of 4 to 5 feet (1.2-1.5m).
‘The Path’ was lovingly brought for me from South Africa by a dear friend Tilly Hutchinson.
Sadly, it died in my absence during a summer. Two years ago, I hunted it down in Bangkok, Thailand and I have successfully propagated from it by softwood cuttings.
The mother plant enjoys a west-facing border planted in full sun and a humus-rich soil.
Hibiscus rosa-sinensis comes in a medley of colours ranging from blood-red to crystal-white and may be single, double or semi-double.
Some of our semi-double forms resemble a large butterfly resting between the outer petals – simply gorgeous.
The flowers may be anything from miniature to plate-sized up to 12 inches (30cm) across.
Hibiscus rosa-sinensis produces seeds only in certain regions of the tropics, but as far as I know, do not set seed in Bahrain and nor Malaysia – so we are in good company.
In Hawaii, Florida and Queensland it does set seed and are used for propagation.
Here, our atmosphere is too humid to allow it to set seed; the weather has to be drier and cooler. Usually, hibiscus is propagated by seed, stem cuttings, marcotting or air-layering, budding and grafting.
Cuttings: Many varieties of hibiscus are easily propagated by cuttings of different types. Softwood cuttings are generally taken; tip cuttings of half-ripened wood that is still green at the tip are the most appropriate vegetation for propagation.
These will also produce a vertical growth, giving a single unbranched stem, which is excellent for training a standard plant.
Such cuttings will form roots within four to six weeks – even void of a hormone rooting medium.
The resulting plants will produce flowers within a few months.
Mature, fully ripened woody cuttings with a diameter of a pencil will also provide excellent propagation material. These will generate plants with a few axillary branches.
Pruning is carried out not only to achieve a more harmonious plant but also to encourage budding as hibiscus flower on new shoots.
I tend to prune our Hibiscus rosa-sinensis plants in the autumn. Some hibiscus growers prune only one third of a shrub at a time leaving some terminal buds as they flower at the terminals of their branches.
A root pruning may be carried out at the time of replanting a potted specimen. Never remove more than one third of the roots.
Bud drop is usually caused by drought or a severe pest invasion. Yellow leaves occur naturally from time to time and are an indication of the leaf’s age rather than alarm bells.
However, yellow leaves in large numbers may be due to a plant’s stress, caused by drastic environmental changes or pest invasions, especially spider mites.
The latter can be treated with soapy water, or showering the plant with a strong burst of water or diluted neem tree oil.
Comprehensive chapters on pruning, propagation and organic pest and insect control feature in my book Tropical Trees and Shrubs of Bahrain.
I wish you every success in growing this Queen of flowers.
Elizabeth Shaheen – GDN – 21 May, ’06