Eremophila: The Emu Bush

In the early 1980s, Ray Isaacson of Geranium, South Australia, showed that grafting eremophilas onto Myoporum rootstock was possible and from his humble start this process has become the norm for establishing newly introduced species and for extending the range of species which can be grown in the more temperate areas.

Eremophilas are diverse in their habit, ranging from prostrate groundcovers, like E.serpens and E.biserrata, to shrubs, both small and large, e.g. E.glabra, E.maculata and E.nivea to large bushes including E.psilocalyx, E.gibsonii and E.duttonii. There are several tree species, including E.mitchellii, E.longifolia and E.bignoniiflora. Flowers range in colour across the spectrum, as well as white.

A survey carried out in 1995/96 by the Eremophila Study Group revealed that there were 165 species being grown by members of the Group, some tenuously so, but others growing extremely well and now fully established as plants with horticultural merit. It is very pleasing to note that many of the species gazetted as Rare and Endangered, including E.nivea, E.racemosa, and E.denticulata are now well known as garden plants.

My observations in nurseries in South Australia and Victoria indicate that there are about 20 or so species available through general nurseries, with about 80 available through those which specialise as native nurseries. There are now many colour forms marketed and it is noted that the 'colour' labels attached to so many plants these days often have concocted names which are not registered with the Australian Cultivar Registration Authority. This will, I fear, lead to much confusion in the future.

Cultivation and Uses

The cultivation of eremophilas is best suited to the drier areas of Australia, however, they have in the main, proven to be adaptable to a range of soil types provided that drainage is very good and that light conditions are adequate; most require a full sun site in the more temperate climates. More eremophilas have been killed through overwatering than through any other cause. Some species have proven to be short lived, but these often propagate readily from cuttings. Others, once established have proven to be very reliable and long lived.

It is possible to establish plants on their own roots as well as those grafted onto Myoporum stock in garden situations, the grafted plants appearing to be the better option in the wetter locations. Pot plant culture is also suited to many of the species of smaller growth habit.

As a rule eremophilas will grow on relatively poor soils, but they do respond to fertilisers, provided they are not applied too heavily and too often.

Whilst it is dangerous to generalise, most eremophilas are relatively pest free - aphids and mealy bug are the most commonly met. These can be controlled by predators or by applying 'soft' insecticides. Borers, particularly the larvae of the Cossinae family, do attack roots and stems of some Myoporum species and this may prove to be a problem for plants grown on Myoporum rootstock. (In June 1997, moths emerging from larvae and pupae, which I collected in Myoporum bateae roots and stems in my home garden were identified at the South Australian Museum as Archaeoses polygrapha (Low.). These larvae had been found before in Myoporum insulare and Myoporum montanum, commonly used as the rootstock for grafting eremophilas, but not identified positively.)

As a genus, Eremophila has the potential for use in the revegetation of minesites etc. (Richmond 1993). In his thesis, Dr Guy Richmond dealt largely with dormancy and germination of seed and the ecology of Eremophila in Western Australia. His studies centred on Mt Weld Station and Mt Keith Station in the Willuna area. He researched the potential for a range of local species to be used in this way. One statement in his conclusion, (P 218) reads:

''The future potential of this genus is significant, since it offers a wide range of uses in rangeland and minesite rehabilitation programs, horticulture, medicinal and phytochemical industries."

Eremophilas have long been recognised as fodder plants in the pastoral areas of Australia; E.maculata, E.latrobei, E.forrestii, E.longifolia, E.oldfieldii and E.scoparia are grazed, particularly as seedlings or when in the flush of new growth. (Richmond 1993).

In recent times research has been carried out on the medicinal properties of eremophilas. One such study, (Pennachio et al.), discusses the research into the cardioactive effects of extracts from E.alternifolia. In their introduction, reference is made to the Aborigines' use of decoctions for headaches, fevers, inducing sleep and general well-being. Another paper (Richmond and Ghisalberti 1994) deals with the Medicinal, Horticultural and Phytochemical uses of Eremophila. This is a most comprehensive look at the future potential of a very diverse genus of native Australian plants.

Propagation

The propagation of eremophilas may be achieved from seed, from cuttings, by grafting and by tissue culture, which is still in its infancy.

There is much anecdotal material about growing ermophilas from seed, the legendary information about the seeds having to pass through the gut of an emu, is, as far as I am aware, without proof. Members of the Eremophila Study Group have from time to time reported on their successes and failures in the Study Group's Newsletters, but there is no consistency of procedure or results.

Reference to the work of Dr Guy Richmond in this area is cited above. In The Czech Republic, Paul Rezl has done some successful work on seeds extracted from fruits, raising seedlings of such species as E.compacta, E.eriocalyx and E.platycalyx.

Cuttings may be taken at most times of the year, but spring through summer are best, especially when new growths have started to mature. In autumn into winter, bottom heat is generally required. Not all species respond at the same time of the year and so there is some trial and error required to establish the optimum time. Some strike easily without hormone treatment, others respond best with hormones. Many growers have trialed different hormones and concentrations, but there is little detail reported - this area seems to be something of a 'Holy Grail' to some.