John Fitzgibbon, Metropolitan Tree Growers Pty Ltd
As tree growers, we are frequently asked for “new” lines that will grow well under most conditions, look fantastic, fit under power lines, grow without any irrigation, be vandal-proof, etc, etc. And of course, these trees should be available at 3.0m height, in a root-conscious container, look fantastic at sale time, cost $75.00 (yes, inclusive of GST), and be available NOW in groups of 50.
At Metropolitan Tree Growers Pty Ltd, we have a range of trees that I feel should be included in the TREENET trials. I believe this is so because we have worked very hard over the last 5 years to select the best forms, provenance selections and cultivars for south-eastern Australia. We sometimes go with the latest selections, but often instead we will grow some plants that have gone out of the horticultural limelight. Selections like this include Callistemon salignus — not often planted since the 1970s, but a tree with a great deal of merit.
For my presentation today, I have categorised the trees I’d like you to consider into 4 groups
- those that have done well in Melbourne but which are still different from the run-of-the-mill selections,
- new Metropolitan Tree Growers selections,
- plants that have performed well overseas but are not adequately trialled in Melbourne, and
- our wish-list of trees that we can’t get appropriate propagation material to grow from.
Below you will find my selections; if they are included in the Metropolitan tree Growers Pty Ltd Tree Handbook 2002-2003, I have not included a description.
These tree selections make up the backbone of the Metropolitan Tree Growers list, and have proven better than many of the seedling or “normal” forms available. We have grown all of these selections since the late 1990s, and we can see that they are performing well in the Melbourne streetscape.
- Corymbia maculata Mottle Ranges and Bodalla forms
- Eucalyptus leucoxylon ‘Eukie Dwarf’
- Melia azedarach Upright Form
- Ulmus parvifolia Murray’s Form
At Metropolitan, we are constantly looking for better selections to grow — many of the plants listed below are not new at all, but instead are new to our list, and are finally available as 1.8-2.0m trees for horticulturists to use in the landscape. We are unsure of how these plants will grow in the streetscape, but we believe that they will fill gaps in the available tree selections.
Yellow Bloodwood is a tree to 15m at most that has many of the fine qualities of other Bloodwoods, only smaller. Yellow Bloodwood grows on shallow, rocky soils in a warm-temperate climate, and should do well in most freely-draining sites. Since it is somewhat smaller than Lemon Scented or Spotted Gums, it may be more useful in narrower sites.
Low fruiting: We discovered this tree in a streetscape planting of Melias. It forms an excellently-shaped tree, with the typical foliage and inflorescences. The flowers do not fully open, and they have set no seed in the street. We are quite certain that these trees are low-fruiting, but would not want to identify them as “sterile” just yet.
Cork Oak from southern Europe. Although probably too broad for many streets, this tree is tolerant of very droughty soils. An excellent evergreen oak that will grow extremely well as a park tree or for broad avenues.
James Will and I constantly read the overseas journals and trade magazines advertising better tree selections. One of these, the Wilga is Australian, but has been used most extensively and best in the south-western states of the US.
Montpellier Maple comes from the Mediterranean basin, where it grows on dry, poor soils. It seems to have grown very well here at the Waite Arboretum, and should be an excellent, small maple for the streetscape. We believe it should be more reliable in dry soils than A. buergerianum.
Sour Orange, or Trifoliate Orange (C. auranticum we think) both have potential for growing as street trees, since they are of the appropriate size, have elegant foliage and flowers, and are strongly tolerant of hot, dry sites. I have been surprised at how well many citrus, including the Cumquats (Fortunella species) do in pots that haven’t been watered well, and some of these smaller growing citrus may be better than the often-used Ficus for many of our streetscapes.
These are trees that we want to grow in our nursery, but we haven’t been able to get appropriate propagation material for them. Also, these trees come from warm, dryland areas, and Melbourne may not be the ideal place to produce them, although they should do well once in the streetscapes.
Weeping Myall is a common tree in south-eastern Australia, and is found on both dry-skeletal soils of the Mallee and more organic soils. It seems to thrive once established, becoming a 6-8m tall tree with rounded head. Bob Perry, from California has used this tree well in planter boxes and nature strips throughout southern California, yet it is rare to see in Australian urban sites.
I see great potential for some of these hybrids, especially those between B. populneus and B. discolor, as these trees seem to thrive on dry sites with little maintenance. To date, we have not been able to find a reasonable supply of good grafted plants to grow-on appropriately.
Again, getting grafted plants has proven a problem. In Melbourne we have found that H. francisiana grafted onto better understocks (frequently H. sericea) will yield a plant growing to about 5m with excellent “martini glass” form, good foliage and elegant flowers. At our site in Alphington Victoria, a number of these grafted trees were planted in the early 1970s. They are thriving in narrow nature strips (the turf has long died out with drought, foot traffic and compaction).
Pittosporum angustifolium (syn. P. phillyraeoides):
This small growing tree (to 8m) can be found on warm sites in all states of Australia. Its somewhat weeping habit, crocodile-like bark and attractive fruits make it worthwhile for using in difficult sites. The canopy is not dense, but it has characteristics that make it worth considering – especially if the site is narrow.