NOTICE: Hard copies of the Australian New Crops Newsletter are available from the publisher, Dr Rob Fletcher. Details of availability are included in the
Advice on Publications Available.[Colleen Keena is employed as a School Counsellor. She spends as much of her other time as possible in her bush garden. Her current interests include adding to her large collection of bushfood plants and local area species, particularly those with unrecognised horticultural potential.]
There are a number of economically important members of this family. Some are best known as fibre plants, such as cotton (Gossypium spp.), kenaf (Hibiscus cannabinus) and Chinese jute (Abutilon theophrasti) whereas others are useful as food plants, such as okra (Abelmoschus esculentus or Hibiscus esculentus) and several edible Malva spp. (M. nicaensis, M. parviflora, M. sylvestris and M. verticillata var. crispa).
There are lesser known species which are still important crops, particularly in tropical countries. For example, Aibika (Abelmoschus manihot), with its high level of leaf protein is eaten as a green vegetable; Hibiscus tiliaceus produces fibre and is also used medicinally; and rosella (Hibiscus sabdariffa) produces colourful calyces which can be used for jam, jelly or cordials, fibre which can be used for paper pulping and high protein leaf which can be used for animal feed.
Despite the fact that there are many members of the Malvaceae family growing naturally in Australia, until now there has been little recognition of the importance of the Hibiscus spp. and their close relatives.
However, the most recent report from the Rural Industries Research and Development Corporation entitled 'Prospects for the Australian Native Bushfoods Industry' includes native rosella (Hibiscus heterophyllus) in the list of the fourteen plant species identified by the Australian National Bushfood Industry Committee as having the most potential as crop industries.
This report also mentioned wild rosella (Hibiscus sabdariffa), an introduced species growing wild in northern Queensland and in the Northern Territory. The petals can be used for making jellies and dessert garnishes and were described as having a tart flavour with a raspberry/rhubarb/plum quality.
Commercial plantings of the native or wild rosella, at the time of the report, were not known. However, wild rosella is known to be traded and to be used in the production of value-added products. The report recommended that a density of 1500 plants per hectare be used for commercial production, producing an estimated cost per hectare for plant material of AUD3750.
Wild rosella takes three years to mature. Fresh, uncleaned flowers return AUD4/kilogram and cleaned and frozen flowers AUD8-12 per kilogram. A kilogram of flowers contains about four hundred flowers.
The profuse blooming habit of native rosella was first reported by Allan Cunningham in 1824. As well, in 1828, the Colonial Botanist of New South Wales, Charles Fraser, wrote of a related species, Hibiscus splendens, that he considered to be king of all the Australian plants he had seen; the most delicate pink and crimson flowers literally covered the whole plant. (Lebler, B.A. (1977) Wildflowers of South-Eastern Queensland. Queensland Department of Primary Industries).
Despite having many early records of Hibiscus spp. and related genera, new species are still being reported. Australian representatives can be herbs, shrubs or trees from genera such as Abelmoschus, Abutilon, Alyogyne, Gossypium, Lagunaria and Radyera.
Abelmoschus moschatus is a ground cover (grown for musky seeds, ambrette), Hibiscus trionum and H. geranioides are small plants (0.5 metre high), Alogyne huegelii is a medium shrub (1-2.5 metres high) and Lagunaria patersonii is a tall tree (growing to 13 metres high).
These plants can be found growing in tropical areas (Abelmoschus manihot), in swamps and crater lakes (Hibiscus diversifolius), along the beach (Hibiscus tiliaceus), in inland Australia (Gossypium sturtianum, Alyogyne hakeifolia), in fissures in sandstone in open forest or along rainforest margins (Hibiscus spendens), or along the margins of light rainforest on soils ranging from loam to granitic gravel (Hibiscus heterophyllus).
Although most prefer subtropical or tropical conditions, some of these species, such as Hibiscus splendens or H. diversifolius will survive temperate conditions, so long as water is adequate. Currently, remnant stands of Hibiscus heterophyllus on hillsides near Brisbane in south-east Queensland are surviving, despite the recent prolonged drought. In the Wide Bay district, roadside plants of Hibiscus divaricatus have regrown following bushfires. Alogyne huegelii has been described as being able to survive in the 'most desolate of places'.
In the Brisbane area, Hibiscus heterophyllus commences flowering in winter and continues until the beginning of summer; H. splendens flowers in spring; H. divaricatus flowers in spring and autumn; some forms of H. diversifolius flower in spring whilst other forms flower into autumn. Whereas these flowering periods are relatively short, Hibiscus tiliaceus flowers over a much longer period.
These four short-flowering species were chosen twenty years ago as the parental material for a selection program to extend the flowering period. Other selection criteria included larger flowers, with a wider colour range.
From a plant of Hibiscus heterophyllus and a Hibiscus splendens x H. divaricatus hybrid, the selections 'Apricot Mist' and "Gold Mist' with continuous flowering have been derived. The latter has improved flower size as well and the flower colour has been changed, as the names indicate.
A selection from Hibiscus diversifolius which flowers continuously has been named 'Colour Magic' since the flowers are maroon in summer, yellow in winter and pink in autumn and spring.
It has been observed during this breeding program that seedlings differ from cutting-grown plants in their growth habit, necessitating care when comparisons are being made for selection purposes. Whereas seedlings produce a tap root and are slow to commence flowering, cutting-derived plants have fibrous roots and produce a bushy plant habit which flowers earlier and over a longer period.
Grafting can also improve the flowering performance of Hibiscus and related genera. 'Gold Mist' has so far proven to be the most useful rootstock, and several forms of Alyogyne huegelii have been successfully grafted onto this rootstock.
The focus of this selection program has been the recognition of Hibiscus heterophyllus as having the potential to be an economically viable floriculture species. As well, the high protein leaves of Abelmoschus manihot and Hibiscus sabdariffa, the quality of the seed protein of Hibiscus esculentus, the fibre of Hibiscus tiliaceus and Hibiscus heterophyllus, and the medicinal potential of Hibiscus tiliaceus probably warrant further investigation.
There are no reports of Hibiscus spp. being poisonous but care needs to be taken. Flowers, leaves and roots of Hibiscus spp. have been reported to be edible, if the taste is acceptable. However, Peter Hardwicke has reported in the Australian Food Plants Study Group Newsletter (February 1995) that he suffered kidney damage from drinking tea, over several days, made from Hibiscus heterophyllus. Aborigines confirm that the plant is used only sparingly as a medicinal plant and is not eaten.
Hence, care should be exercised with any human consumption of the species Hibiscus heterophyllus, H. splendens, H. divaricatus, H. diversifolius or H. tiliaceus. These plants may, however, have some function as landscaping species. Hibiscus tiliaceus has been established as a landscape plant in roadside plantings, in car parks of shopping areas and at Brisbane airport. The other species could have similar use, with H. diversifolius as a ground cover.
The inclusion of Hibiscus hetero-phyllus as a potential bushfood indicates that it is considered as warranting further attention. Have we ignored the economic potential of some other of these members of the Malvaceae family?
Any claims made by authors in the Australian New Crops Newsletter are presented by the Editors in good faith. Readers would be wise to critically examine the circumstances associated with any claims to determine the applicability of such claims to their specific set of circumstances. This material can be reproduced, with the provision that the source and the author (or editors, if applicable) are acknowledged and the use is for information or educational purposes. Contact with the original author is probably wise since the material may require updating or amendment if used in other publications. Material sourced from the Australian New Crops Newsletter cannot be used out of context or for commercial purposes not related to its original purpose in the newsletter
Contact: Dr Rob Fletcher, School of Land and Food, The University of Queensland Gatton College, 4345; Telephone: 07 5460 1311 or 07 5460 1301; Facsimile: 07 5460 1112; International facsimile: 61 7 5460 1112; Email:
r.fletcher@mailbox.uq.edu.au[
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GK; latest update 6 June 1999 by: RF