Ornamental Trees

Hundreds of tree species could potentially be grown in Queensland, but a great many would not be practical in urban environments and/or are not readily available on the commercial market.

The following selected genera contain some of the more popular tree species for ornamental purposes in Qld. Follow the links for more information. Please note, however, that many species referred to on these pages will nevertheless be unsuitable for small gardens, so please do your research before planting. (See also Shrubs because some larger shrub species can be trained as small trees).

Trees suitable for suburban gardens in the tropical, subtropical and warm temperate (frost free) parts of Australia are among the plants covered in Get Results Gardening. If live in those zones, why not ask for a free trial? Go to calyx.com.au/getresultsgardening.html (or click on the banner below) for more information.

Sometimes, the sizes quoted in various publications reflect ultimate size in their natural habitat. They may reach for the sky in a densely crowded rainforest, while in a more open garden situation, the same tree is likely to be shorter but with a fuller canopy. Other variables are time (it may take decades to reach that size) and local conditions (climate, soil water), which will affect the vigour of any plant.

A mistake that many people make is planting something too vigorous and ultimately too large because they're impatient, typically for privacy reasons. The downside is that such species may present maintenance problems down the track, needing frequent pruning to keep them within bounds and maybe even creating root problems. By sticking to tree species that are relatively small even when mature, they shouldn't be too much of a problem even if neglected.

Some Tree-Related News

Helping Boab Heritage Live Forever

In Australia's Tanami desert (which extends from the NT into WA), there are boabs that are also precious works of Indigenous art. Now researchers are working with Traditional Owners to document them before the trees succumb to old age. The actual age of the trees is uncertain, but there's no time to waste in recording the carvings on their bark. "Unlike most Australian trees, the inner wood of boabs is soft and fibrous and when the trees dies, they just collapse," said Professor Sue O’Connor of the ANU. "We hope that our research will bring the art in the bark of these remarkable trees to many more Australians so that they can be appreciated for generations to come." So far, twelve trees with carvings have been catalogued in this very remote region, but further expeditions may find more. Source: Race against time to find Indigenous carvings on boab trees (October 2022)

Tree Inequality in Brisbane

Provision of street trees in Brisbane may be related to the socio-economic level of the suburbs, suggests a preliminary study by urban planners at the University of Queensland. Of the three suburbs compared, the one with the lowest average income (Deagon) had the lowest number per kilometre of street (77). However, the middle income Riverhills (113) had more trees than the high-income Parkinson (87). This was a pilot study and more extensive data between and within suburbs may reveal more definitive associations with income, street design and street usage. The researchers are particularly concerned with the relationship between shady trees, pedestrians and public transport uptake. Source: Tree study shows low-income Brisbane suburbs need more shade (September 2022)

A Prescription for Street Trees

Consistent with growing evidence of the therapeutic effects of a vegetated urban environment, analysis of the population in Leipzig, Germany has shown that streets trees can improve mental health. Researchers used the number of prescriptions for antidepressant medication in different parts of the city as the gauge. They found that a high number trees within 100 metres of the home made a difference, particularly among socio-economically disadvantaged groups. These are also the ones most at risk, so planting of more street trees could help address inequalities in this aspect of health. The species or diversity of the trees did not make a difference in this study, nor did the number of trees more than 100 metres away from home. Source: Street trees close to the home may reduce the risk of depression (January 2021)

Not everyone loves street trees

Between 2011 and 2014, nearly a quarter of eligible residents in Detroit (USA) submitted no-tree requests and researchers decided to find out why. Economic problems resulted in big cuts to the city's maintenance budget. The large numbers of dead and hazardous trees consequently left untended contributed to urban blight. This made residents wary of new trees and the authorities planting them. Residents feared they would be left with responsibility for caring for trees and wanted a greater say in which trees were planted. Education, choice and communication were seen as a way forward. Read more: Why People Reject City Trees, University of Vermont (January, 2019)

Ipswich preserves an original resident

Ipswich City Council has preserved a huge Eucalyptus tereticornis (Queensland Blue Gum or Forest Red Gum) by during an upgrade to Riverside Drive at Pine Mountain. A low pressure sucker vac was used to locate the root plate of the 35 metre high tree, allowing a concrete floodway to be modified to avoid damage. Council has undertaken to maintain the specimen, an original tree of the area which managed to escape the timber industry. Source: Health of 'pioneer' Blue Gum a priority during roadworks (December 2017)

The anti-aging effects of trees

A Toronto-based analysis of urban greenspace and health indicates that having 11 more trees in a city block decreases cardio-metabolic conditions equivalent to an increase in personal income or being 1.4 years younger. Just 10 trees produces a self-reported increase in health perception equivalent to being 7 years younger. Source: Neighborhood greenspace and health in a large urban center (July 2015)

For healthier people, plant trees

A US study has estimated that trees save the lives of more than 850 Americans and prevent some 670,000 acute respiratory incidences per year by removing air pollution. These positive health effects were valued at nearly $7 billion annually. Source: First national study finds trees saving lives, reducing respiratory problems: Air pollution modeling reveals broad-scale impacts of pollution removal by trees (July 2014)

Trees save lives

Analysis of tree populations, air pollution data and human health and population statistics of several American cities has estimated that the beneficial effects of fine particulate matter removal by urban forests saves around one life per city per year. Source: Forest Service Study Finds Urban Trees Removing Fine Particulate Air Pollution, Saving Lives (June 2013)

More shade for Brisbane pathways

Brisbane City Council has declared that its footpaths and cycleways will be cooler and greener in the future as a result of its Neighbourhood Shadeways initiative. The aim is to increase the city's street tree population by 35000 by 2026, taking shading along residential footpaths and cycle ways to 50% from a current 35%. A range of native shade tree species will be used. Council is encouraging residents to let them know where they would like more trees planted More information: Lord Mayor's growing plan to shade Brisbane streets (October 2012)

New woody weed control developed in Qld

A new biocontrol agent developed by the University of Queensland could mean a simple and safe way to control woody weeds. Developed from fungi which already occur in the Australian environment, the treatment is delivered as a capsule inserted into the trunk of the tree. In addition to killing the inoculated tree, the fungi could persist to kill seedlings that subsequently emerge in the area, or even untreated mature trees nearby. Commercialisation of the "bioherbicide" for control of Parkinsonia is underway, but it has the potential to control many types of other woody weeds. More information at the University of Queensland website: Australia's first bioherbicide approaching release (August 2012)

Toowoomba tree plan takes trophy

The Toowoomba Street Tree Master Plan has won the Sustainable Initiatives Category in the national Parks and Leisure Australia Awards of Excellence A bloomin' great effort bags national awards (September 2012)

Tree replacement won't let poisoners win

It has been confirmed that a dead Casuarina glauca on the Golden Beach foreshore was poisoned. Unfortunately, it will have to be removed. Sunshine Coast Council will promptly replaced it by a new specimen of the same species, with a high level of protection and monitoring during its establishment. Anyone convicted of poisoning a tree could face very heavy fines. Source: Calling for community support in protection of tree (August 2012)