Eremophila sturtii

Eremophila sturtii
Eremophila sturtii flowers and leaves
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Lamiales
Family: Scrophulariaceae
Genus: Eremophila
Species: E. sturtii
Binomial name
Eremophila sturtii
R.Br.[1]

Eremophila sturtii commonly known as turpentine bush, narrow-leaved emu bush, budda bush, small sandalwood and scented sandalwood is a shrub endemic to Australia. Aboriginal people give it the names Munyunpa and Watara.[2] It is widespread and common in the drier parts of Australia and occurs in all mainland states, although it is endangered in Victoria. It is a medium to large shrub with narrow leaves and lilac-coloured to pale mauve flowers but it some places is regarded as a weed, partly because of its ability to reproduce vegetatively.

Description

Eremophila sturtii is a shrub growing to a height of 1–3 metres (3–10 ft) with many slender branches and dark grey, deeply fissured bark on older specimens. Its leaves are arranged alternately, bright green, slightly aromatic, mostly 10–50 millimetres (0.4–2 in) long and 0.5–2.5 millimetres (0.02–0.1 in) wide. They are also linear in shape with a curved, hooked end, glabrous, shiny and often sticky due to the presence of resin.[3][4][5][6]

The flowers are borne singly, rarely in pairs, on curved stalks 6–18 millimetres (0.2–0.7 in) long in the leaf axils. There are 5 cream-coloured to pinkish-purple, lance-shaped to egg-shaped sepals. The sepals are sticky, mostly glabrous and usually 7–11 millimetres (0.3–0.4 in) long. The five petals are 12–18 millimetres (0.5–0.7 in) and joined at their lower end, forming a bell-shaped tube. The petal tube is lilac-coloured to mauve or pinkish purple, rarely white and is spotted with purple. The petal tube has glandular hairs on the outside but the outside of the lobes is often covered with many long, thin hairs. The inside of the lobes is glabrous, except for the lower one which is covered with long thin hairs. The inside of the petal tube is filled with long, soft hairs. The 4 stamens do not protrude beyond the end of the petal tube. Flowering occurs from July to October and is followed by fruits which are hard, hairy, oval shaped and 3.5–5 millimetres (0.1–0.2 in) long.[3][4][5][6][7]

Eremophila sturtii growth habit

Taxonomy

Eremophila sturtii was first formally described by Robert Brown in 1849 and the description was published in Charles Sturt's Narrative of an expedition into Central Australia.[1][8] and named for Captain Charles Sturt in honour of his explorations in central Australia.[3]

Distribution

Eremophila sturtii is common and widespread through south west Queensland, western New South Wales and eastern South Australia. There is a small population in the far north-west of Victoria.[9] There is also a disjunct distribution in south-central Northern Territory, eastern Western Australia and north central South Australia.[3] It grows on clay soils on plains, red sandy soils of sand plains and on low shaley hills.[2]

Conservation

This species is calssified as "not threatened" by the Government of Western Australia Department of Parks and Wildlife.[10] It is listed as endangered in Victoria.[9]

Notes and Discussion

Eremophila sturtii is a contentious plant. It is widely classified as a woody weed in Queensland and New South Wales because of its ability to regenerate and survive. Research has centred on management of the species for grazing productivity, controlling regeneration, pharmacology and domestic propagation.

Woody weeds are those shrubs that form large, dense stands, often taking over previous grasslands, and dominating the landscape. This negatively affects agricultural productivity and leads to loss of usable land. Eremophila sturtii is unpalatable to stock and has a reputation as difficult to eradicate. It is sometimes confused with Eremophila mitchellii (buddah bush).

Eremophila sturtii is an indicative species[11] of the dune mallee woodlands, semi arid sand plain woodlands, northwest plain shrublands, stony desert mulga shrublands and sand plain mulga shrublands of New South Wales.

Grazing management and woody weed control

All these areas have low and irregular rainfall and are subject to regular drought. The principal agricultural use for these lands is sheep grazing. Poor land management practices in the pursuit of grazing productivity has negative impacts and increases the likelihood of a problem with woody weeds. While this is a widely quoted fact, there seems to be no significant research to substantiate this claim. The claim appears to be based on empirical evidence based on an increase in woody weeds, and resulting loss of productive land, over an extended period.

What is clear is that a loss of grass cover in these semi arid areas, through grazing, low rainfall or fire, increases the opportunity for propagation for species that are known as woody weeds, especially E. sturtii. Research in the 1970s and 1980s into grazing methods that could control the spread of woody weeds focused on the possibility of mixed sheep and goat grazing to spread the pressure on fodder species thus allowing better regeneration options for those species. Instead, the research found that neither sheep nor goats touched E. sturtii as fodder and actively avoided it. Further, the research found that the relative values of the sheep and goats at market made it uneconomical to mix grazing.[12]

Control of the spread and dominance of Eremophila sturtii in agricultural grazing lands has acknowledged that the resistance of the plant to control methods is due to the very adaptations that allow it to survive in its semi arid environment. Research into methods to control the spread of E. sturtii initially focused on regeneration following severe fires in 1974 in the Ivanhoe (NSW) district. The results showed that E. sturtii was particularly good at regeneration after fire and ‘recovery seemed independent of burning conditions and shrub size’.[13]

Later studies of ‘grubbing’ techniques in the Cobar region of New South Wales have shown that ripping the plants from the soil, and then covering the exposed roots with soil, has been the most effective method of control.[14]

Concern has been raised[15] about the consequences of removal of woody weeds. As a dominant species they are stable in the environment. What happens, in terms of replacement, in the event of removal is still unclear.

Pharmacology and other uses

E. sturtii is one of the most aromatic of the eremophila species and it is thought that this is an indicator of potential medicinal use. The literature also acknowledges medicinal use of E. sturtii in Aboriginal tradition. Evidence exists that this plant was used in the treatment of coughs and colds by grinding the leaves and mixing with fat to spread on the skin.[16] Recent research has focused on the pharmacology of many eremophila species, including E. sturtii. Isolating compounds found in endemic species of plants is becoming prevalent in the search for means to assist in the fight against antibiotic resistant bacteria. This is a costly and time consuming practice. Research into E. sturtii has been focused on the development of an antibacterial layer that can be applied to medical implants to prevent infection.[17][18][19] References exist in the literature to E. sturtii having termite resistant qualities. This has been evidenced from examination of fenceposts made from the species after considerable time in the ground. The species has not been widely used for fencing as its growing habit encourages a multi stemmed shrub instead of a thick single stem that could be productive.

Domestic propagation

Flowers of E. sturtii carpet the desert
Flowers of E. sturtii carpet the desert

The Society for Growing Australian Plants (now Australian Native Plants Society (Australia)) Eremophila Study Group has focused attention on propagating eremophila species with varying degrees of success.[20]

E. sturtii has been seen as highly desirable because of its density of flowers. "It resembles a bridal veil blowing in the wind when in flower".[21]

There has been some success in propagation, with E. sturtii, using cuttings from woody timber and the difficulty of using seed has been noted. Suggestions have been made to use cuttings grafted on myoporum[21] for domestic gardens to avoid the problems of suckering. Its frost tolerance, and hardiness in drought, makes it a species that is noted for inclusion in difficult gardens. Conditions in the natural environment that allow for propagation – rainfall patterns (spring rain after winter rain) and soil temperatures are difficult to maintain in a domestic environment.

The study group has noted that members have suffered from skin irritation and allergic reactions when handling E. sturtii.

References

  1. 1 2 "Eremophila sturtii". APNI. Retrieved 7 January 2016.
  2. 1 2 Kutsche, Frank (2003). Field Guide to the Plants of Outback South Australia. South Australia: Department of Environment and Heritage, South Australia. p. 80. ISBN 0759010528.
  3. 1 2 3 4 Chinnock, R.J. (Bob) (2007). Eremophila and allied genera : a monograph of the plant family Myoporaceae (1st ed.). Dural, NSW: Rosenberg. pp. 216–218. ISBN 9781877058165.
  4. 1 2 Brown, Andrew; Buirchell, Bevan (2011). A field guide to the eremophilas of Western Australia (1st ed.). Hamilton Hill, W.A.: Simon Nevill Publications. p. 267. ISBN 9780980348156.
  5. 1 2 Chinnock, Robert J. "Eremophila sturtii". Royal Botanic Gardens Sydney: Plantnet. Retrieved 7 January 2016.
  6. 1 2 "Eremophila sturtii". Electronic Flora of South Australia. Retrieved 7 January 2016.
  7. ↑ Cunningham, G.M. (1981). Plants of Western New South Wales. Australia: Soil Conservation Service of New South Wales. pp. 610–611. ISBN 0724020039.
  8. ↑ Sturt, Charles (1849). Narrative of an Expedition into Central Australia (Volume 2) (PDF). Bond Street, London: T. and W. Boone. p. 85. Retrieved 7 January 2016.
  9. 1 2 "Eremophila sturtii". Royal Botanic Gardens Victoria: VicFlora. Retrieved 8 January 2016.
  10. ↑ "Eremophila sturtii". FloraBase. Department of Environment and Conservation, Government of Western Australia.
  11. ↑ Keith, David (2004). Ocean Shores to Desert Dunes. Sydney: Dept of Environment and Conservation (NSW). pp. 268–295. ISBN 0731367804.
  12. ↑ Wilson, Alan Durham; Mulham, William Edward (1980). "Vegetation changes and animal productivity under sheep and goat grazing on an arid Belah (Casuarina cristata) - Rosewood (Heterodendrum oleifolium) woodland in western New South Wales.". The Rangeland Journal 2 (2): 183–188. doi:10.1071/RJ9800183.
  13. ↑ Wilson, Alan DDurham; Mulham, William Edward (1976). "A survey of the regeneration of some problem shrubs and trees after wildfire in western New South Wales.". The Rangeland Journal 1 (4): 363–368. doi:10.1071/RJ9790363.
  14. ↑ Wiedemann, H. T.; Kelly, P. J. (2001). "Turpentine (Eremophila sturtii) control by mechanical uprooting". The Rangeland Journal 23 (2): 173–181. doi:10.1071/RJ01004.
  15. ↑ Page, M; Beeton, RJS; Mott, JJ (2000). "Grass response to shrub removal in two semi-arid vegetation communities.". The Rangeland Journal 22 (2): 220–224. doi:10.1071/RJ0000220.
  16. ↑ Chinnock, Robert (2007). Eremophila and allied genera. South Australia: Rosenberg Publishing. p. 75. ISBN 9781877058165.
  17. ↑ Greisser, H.J.; Ys, H.; Ndi, C.P.; Britcher, L. (2008). "Combating infections at Biomedical Implants and Devices by Antibacterial Coatings". Chemistry in Australia 75: 5–8.
  18. ↑ Ndi, C.P.; Semple, H.J.; Greisser, H.J.; Barton, M.D. (2007). "Antimicrobial activity of some plant species from the Australian genus Eremophila". Journal of Basic Microbiology 47: 158–164. doi:10.1002/jobm.200610262.
  19. ↑ Ndi,, C.P.; Semple, S.J.; Greisser, H.J.; Pyke, S.M.; Barton, M.D. (2007). "Antimicrobial compounds from the Australian desert plant Eremophila neglecta". Journal of Natural Products 70: 1439–1443. doi:10.1021/np070180r.
  20. ↑ Jennings, Colin. "Eremophila: The Emu Bush". Australian Native Plants Society Australia. Retrieved 8 January 2016.
  21. 1 2 Boschen, Norma (2008). Australia's Eremophilas: changing gardens for a changing climate. Melbourne: Blooming Books. p. 173. ISBN 9781876473655.

External links

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