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 Myoporeae, which mainly occurs in Australia and the South Pacific islands but other areas where they can be found include 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 214 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 commonly 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.

Eremophilas are usually small to medium shrubs although a few may be large shrubs or small trees (eg. E.bignoniiflora).

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 Ranges, as reported by Rosemary Pedler in the Eremophila Study Group Newsletter, December 1994:

"A very common and widespread species, it was of considerable importance to them. The foliage was used to cover the dead before burial which did not take place immediately after death. The relatives would visit the dead person from time to time to observe what was happening to the covering leaves, and there was significance in the way in which the leaves lay. The body was buried at a depth of about an arm's length after about a month and was again laid on and covered by the Varti-varka foliage (Eremophila longifolia).

Also used for medicinal purposes, the bark of trunks was scraped off, reduced to ash and then mixed with emu oil. This preparation was then used for all manner of skin complaints with excellent results, according to several people in the group. This is still being used today.

I was also told by one of the men that the smoke from Varti-varka was used in the initiation ceremony of young boys. This aspect is in the past as the last fully initiated Adnyamathanha man is very elderly now."

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.

The flowers 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 in suitable climates. Flowers occur in the leaf axils. The flowers contain nectar and are frequented by honey-eating birds or insects.

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


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