(Adapted from an article written for Brisbane Rainforest Action & Information Network BRAIN
and published in BRAIN Newsletter 10, January, 1998)
My fascination with this showy, tough rainforest plant began over fifty years ago. I still recall my first glimpses of the large white flowers that lit up the edges of the rainforest as we negotiated precarious tracks on steep hillsides. Consequently this was one of the very first plants we planted when establishing a garden in Brisbane. My interest in this species has continued, particularly as I have watched locally occurring plants flowering profusely for prolonged periods, in spite of the extended drought condition in Brisbane several years ago. I have given plants to friends in both Melbourne and Cairns and the plants perform well in both these locations.
Hibiscus heterophyllus was recorded in the Brisbane area in 1824 by Allan Cunningham, in 1828 by Charles Fraser and again in 1844 by Ludwig Leichhardt. Describing the vegetation along the Brisbane River, Cunningham noted that Hibiscus heterophyllus was very frequent on the immediate bank "clothed with a profusion" of flowers.
Leichhardt noted that the plant was to be found all over the colony and that its strong bark made excellent natural rope. Not only is this a showy plant but as Leichhardt recorded it is also a useful plant. Traditional Aboriginal uses are listed as young shoots, leaves and roots eaten without preparation (WARNING - see below); flowers were eaten raw or cooked; the fibre was used to make dilli bags - the fibre is strong and prepared by maceration; also made into hunting nets. During the Colonial Period, the buds were cooked and made into jam. Current Use is described as buds cooked and made into jam. Buds can be eaten without cooking in salads or boiled as a vegetable. The petals can be eaten in salads. The flavour of the flowers is very mild and it has been suggested that perhaps the best use for them is as a colourful edible ornament for a salad . Although profuse, the flowers last only a day but if they are wanted for use at night, they can be picked as they begin to unfurl in the morning, then stored in the refrigerator crisper and if taken out in the late afternoon, will open and stay fresh until about mid-night. The flowers can be stuffed, made into fritters or made into tea and the buds pickled. Young shoots (WARNING-see below) of Hibiscus also are edible, raw or cooked and are pleasantly acid. They can be used raw mixed in salads, be steamed or boiled as a vegetable or added to soups. The very sour leaves make a good spinach substitute in Greek dishes and an excellent "spinach" pie. The roots can also be eaten raw or cooked. Hibiscus heterophyllus has been described as a versatile vegetable, with buds that can be stewed as rosellas, leaves tasting like sorrel and roots like woody parsnips. For information on culinary uses see Wild Lime by Juleigh Robins, Allen & Unwin, 1996, page 40.
WARNING. It should be noted that although numerous references suggest that no hibiscus is known to be poisonous, Peter Hardwick has expressed concern in relation to Hibiscus heterophyllus. In the Australian Food Plants Study Group Newsletter of February 1995 it was reported that he suffered kidney damage from drinking H. heterophyllus tea over a few days and that discussions with Aborigines confirmed that they use this plant only sparingly as a medicinal plant, rather than to eat.
While I have encountered few home garden plantings, the commercial possibilities are beginning to be explored in relation to the flower. The Rural Industry Research and Development Corporation (RIRDC) Report, "Prospects for the Australian Native Bushfoods Industry" listed fourteen plant species identified by the Australian National Bushfood Industry Committee as having the most potential. This list includes Hibiscus heterophyllus. At the time of the report, commercial plantings were unknown. A table on page 13 of the report describes plant density, yield and farm gate price. The product is the flower (fresh), the density per hectare is 1500 plants. Plants take 3 years to mature and yield 40 flowers per 100 g. Fresh uncleaned flowers return $4 a kilogram and cleaned and frozen flowers return $8-$12. Estimated cost per hectare is $3750 for plant material cost. The RIRDC Report notes that Native Rosella is used in the same ways as Wild Rosella. Wild Rosella is described in the report as an introduced species common in Northern Queensland and Northern Territory with a tart flavour with a raspberry, rhubarb, plum quality and that the petals make jelly and can be used for dessert garnishes.
WIDESPREAD AND HARDY
Hibiscus heterophyllus is found along the east coast from central N.S.W. to Lockhart River. The plants in the southern half of the range are white and those in the northern half of the range are yellow. Flowering is prolific over an extended period. Flowering is from spring to summer, with variations according to the site. In Melbourne, the yellow flowering form is flowering heavily at Christmas, whereas it flowers well in Cairns in June. On mountain ranges inland from Port Macquarie, the hillside is an incredible mass of white blooms in February. In Brisbane, the white-flowering form in remnant vegetation may commence in June but usually there are few flowers on plants in the western suburbs before August with flowering mostly continuing until about Christmas time. The flowers are large, 10-19cm, white, yellow or sometimes pink, with dark red centres. Fruits are 5-celled ovoid capsules 15-20 mm long. Leaves are dark-green, simple, or lobed and large and stems are rough, or prickly. The species name refers to the different shaped leaves found in this species. Native rosella grows as a tall shrub or small tree, 1-5m x 1-3m with a rounded habit. Hibiscus heterophyllus occurs in shady and swampy eucalypt forests, gullies and rainforest edges on soils ranging from loam to granitic or poor and gravelly.
The prolonged flowering and the production of nectar contributes to the value that Hibiscus species have for "faunascaping" . Not only will blooms which produce nectar feed nectar-eating birds and predators but they will also attract insects for insect eaters, provided there are protected water sources and nesting places for birds. In addition, the seed capsules can provide for seed-eaters. Thus, apart from any aesthetic appeal of birds and insects, plants such as Hibiscus heterophyllus which attracts birds and predators encourage natural pest control as the insects use the plant as a food source and are themselves controlled by a wide range of predators. Honeyeaters take advantage of the large nectar-rich flowers. Birds such as lorikeets are attracted to the seed pods and the sight and sound of a Hibiscus heterophyllus literally covered with lorikeets bowing down the branches as they feast upon the seed capsules more than compensates for any damage sustained. Insects seek out the flowers of this species.
It prefers a moist open spot but adapts to dry conditions and partial shade. The plant becomes rather sparse but it can be developed into a compact bush with regular tip pruning from an early stage. It benefits by being pruned by one-third after flowering. It is drought tolerant but should be grown in a sheltered position if heavy frosts occur.
This species can be used in a variety of ways in horticulture. As it grows rapidly it can be used to form a dense screen. The prickles that are usually found on the branches become a plus when used this way. This species makes effective hedges and very attractive roadside plantings. It also performs well as a specimen plant since flowering is prolific and the flowers show up well against the foliage. Older leaves turn a deep red and this adds to the interest. Hibiscus combine well with other species. The combinations are endless. The white and pink forms of Hibiscus heterophyllus are enhanced by white or pink or maroon flowering grevilleas. Hibiscus heterophyllus performs well in containers when new growth is regularly tip-pruned.
Hibiscus heterophyllus can be maintained in pots for use as an ornamental or as a stock plant. If a seedling is grown, not only might the flowers be a long time coming, but it will be difficult to maintain the plant in a pot. If cuttings are taken, the fibrous root system that results appears to be much more amenable to being contained in a pot, particularly if the plant is tip-pruned from the earliest stages. The result is a bushy plant that flowers freely. The cutting-grown plant usually flowers within approximately six months, often while still in 9 cm pots. Pruning is important and regular tip-pruning is preferred as plants that have to be cut back to wood may not survive. The size of the pot governs the size of the plants and so size can be easily restricted by limiting pot size. I find the larger species a bit like goldfish - give them a big container and they will become very large. I can manage these species indefinitely in shade house conditions in 9 cm pots. However, as soon as they are planted into even 15 cm pots they start to shoot up and out and constant tip-pruning then becomes necessary. Plants can be potted on until the desired size is reached and then maintained at that size by pruning. My stock plants have been allowed to reach 1.5-2m as this size provides plenty of cutting material. The largest size of pot that I use is 40 cm. The strike rate appears to be even higher when cuttings are taken from well maintained cutting-grown stock plants rather than from seedlings growing in garden beds.
Propagation is from seed or cuttings. It should be noted that if any other species of hibiscus are in the vicinity, any seedlings may come in a variety of colours, e.g. lemon, pink, as this species crosses very readily with other species such as H. divaricatus and H. splendens. Abrading seeds by rubbing between two pieces of sandpaper assists in germination. Most seedlings will flower within a year but cutting back seedlings will delay flowering. Seedlings have a tap root which can be an advantage in some locations, e.g. on sandstone ridges. Cuttings taken in spring in Brisbane strike readily, especially if the cut is on a sharp angle through a node and if a rooting compound is used. If difficulty is encountered with cuttings in September/ October, cuttings can be taken in January. The cutting grown plant, with its fibrous root system, forms a dense plant, particularly if tip-pruned regularly and it also flowers earlier and more heavily than a seedling. As well, observations over an extended period indicate that a cutting grown plant flowers for much longer periods than the parent seedling, with some cutting grown plants flowering as early as May and even April in Brisbane.
In spite of all these advantages, there are some disadvantages associated with Hibiscus heterophyllus.
IRRITANT HAIRS The seed pod is covered in hairs that may cause skin irritation. I put plastic bags over my hands when extracting seed and use tweezers to extract seeds from the pods. Sticky tape stuck onto the skin and then pulled off is an effective way to remove any irritant hairs.
PESTS There are a variety of sucking or chewing creatures that enjoy the flavour of both buds and leaves, although well grown plants are less likely to be attacked by either pests or diseases. The Harlequin bug depends on sap sucked from species such as hibiscus, but is not usually troublesome . Metallic flea beetles chew a series of small holes in the leaves but do not damage the flowers. Scale insects can become a problem but can be easily managed either by removing by hand or even by cutting off affected parts. Any other damage that may occur can also be pruned off. Regrowth is fast and the pruning can result in a greater number of flowers.
Probably the major obstacle to growing Hibiscus plants is availability of plants. Few nurseries regularly carry this species. When the plant is available, it may be incorrectly or inadequately identified and other species, e.g. Hibiscus divaricatus, or hybrids between Hibiscus heterophyllus and H. divaricatus may be labelled as Hibiscus heterophyllus. There is some controversy in distinguishing between these two species and that may add to the difficulty of accurate identification. There is however an observable difference in the calyces of the two species.
I have found great variation in plants grown from seed, e.g. variation in flower size, variation in flower shape and variation in the amount of pink on the margins of the flower and in the colour of the stems and branches. I believe we should be choosing from superior forms and propagating from these. Not only will an unattractive plant occupy the same amount of space as one selected for superior characteristics, but poor specimens will hinder acceptance of this species.
Hibiscus heterophyllus is so noticeable that it featured in early written records, it is listed frequently as a food source for both people and fauna and yet has the ability to survive in the toughest of conditions. It is hoped that the landscaping potential of this long ignored family of plants will gain greater recognition in Australian horticulture.
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