Eremophila and its Relatives - Background

Introduction

Eremophila is a large genus of plants closely related to Myoporum. They were formerly classified within the plant family Myoporaceae but that family is now obsolete and has been absorbed into the Scrophulariaceae, which is distributed throughout temperate and tropical climates and consists of small to medium shrubs or small trees. Together with Myoporum and a few other genera, Eremophila is placed within the Tribe Scrophulariacae (formerly Myoporae), which mainly occurs in Australia and the South Pacific islands, but also in other areas including South Africa, Asia, Hawaii and the West Indies. There are currently seven genera in the Tribe:

  • Bontia, comprising a single species (Bontia daphnoides) which occurs in the Carribean
  • Calamphoreus, comprising a single species (Calamphoreus inflatus) which occurs in Western Australia (previously known as Eremophila inflata)
  • Diocirea, comprising 4 species occurring in Western Australia
  • Eremophila, comprising at least 250 species, occurring throughout Australia in all mainland states.
  • Glycocystis, comprising a single species (Glycocystis beckleri) which occurs in Western Australia (previously known as Myoporum beckleri)
  • Myoporum, comprising about 30 species occurring in Australia, New Zealand, the Pacific Islands, east Asia and Mauritius.
  • Pentacoelium, comprising a single species (Pentacoelium bontioides) which occurs in China and Japan.

Australian genera are concentrated in the semi-arid and arid regions with the largest number of species being located in Western Australia. Eremophila is by far the largest of the Australian genera and the one most commonly encountered in cultivation. Some of the features of that genus are described below.

Characteristics of Eremophila

Eremophila species are commonly called "emu bushes". All species are endemic to Australia and they produce fleshy fruits which are often eaten by birds and animals. The common name derives from the erroneous belief that the fruits are eaten by emus and that the chemical changes that occur in the seed during digestion enhance the rate of seed germination after excretion. In fact, the fruits of relatively few species are eaten by emus and the time of passage through a bird is insufficient to influence germination.

The plants are also known as "poverty bushes" because of the ability of many of them to survive in very dry, inhospitable environments. Most are found in areas receiving less than 250mm rain per year.

Eremophilas are usually small to medium shrubs although a few may be large shrubs or small trees (eg. E.bignoniiflora) There are a number of fully prostrate species. Their range in growing forms, interesting fruit, range of leaf forms (from grey to bright green) and the presence of brightly coloured calyces in many species makes them excellent plants for the home garden.

The foliage of some species is toxic and stock poisonings have occurred (eg. E.freelingii, E.latrobei). Some other species are useful as fodder plants (eg. E.bignoniiflora, E.oppositifolia).

Eremophilas have also been valued for medicinal and cultural purposes by Aboriginal people. For example, E.longifolia was important to the Adnyamathanha people of the northern Flinders Ranges1. More recently, traditional uses of E. alternifolia leaves, infusions and handmade leaf-pastes have been reviewed in traditional Aboriginal practice for their use to treat infections of eyes and skin, and to speed healing of wounds2.

Those species which occur in the harshest of climates have developed methods to cope with the severe conditions. Many have greyish, hairy foliage which reflect the sun's rays while other have a shiny, sticky coating on the foliage as a protection against drying winds. Many in these regions also respond to rain by flowering within a few weeks of significant falls.

The flowers of Eremophila are more or less tubular in shape with upper and lower lips. They are reasonably large and often very colourful and are sometimes spotted. In some species the corolla may also be subtended by a large and attractive calyx. These features have resulted in a number of species being cultivated as ornamental plants. Flowers occur in the leaf axils. The flowers contain nectar. Red, yellow and orange flowered species are adapted for pollination by honey-eating birds, whereas those with pink, white or mauve/purple flowers are more usually adapted for pollination by insects.

Following flowering, 1 to 12 seeds develop in a fleshy or dry indehiscent fruit.



Footnotes:
  1. Reported by Rosemary Pedler in the Eremophila Study Group Newsletter, December 1994.
  2. Israt, B et al (2016): Antibacterial constituents of Eremophila alternifolia: An Australian aboriginal traditional medicinal plant, Jnl of Ethnopharmacology, April 2016 - see also Eremophila Study Group Newsletter 114 of June 2016.

◄◄ Eremophila and Relatives Index    Top ▲