Here are some links to external resources you may find useful:
This is an excellent, reasonably priced, web and standalone plant database from the UK. DeepRoot features mostly European species, but with some useful additions from Australia and New Zealand.
Search though > 11,000 records to find just the plant you want.
DeepRoot users have access to a great collection of images that can be used to illustrate your own landscape design ideas. Images in your plans are free from copyright issues. Populate SppDb with DeepRoot images and combine with CAD software such as GardenCAD and gCADPlus.
The figure below shows a high resolution image from DeepRoot added to a SppDb plant list.
DeepRoot also has a free web plant database suitable for casual searching. The result of a search for the annual species - Zinnia is shown below.
Although it is possible to download the image and use it to populate databases such as SppDb, doing just that infringes copyright. Much better to spend the money on DeepRoot, get higher quality images and free yourself from copyright issues.
Shareware (free) image editor
We use highly recommend IrfanView. Use it to add a copyright notice to your images and adjust the image size to a maximum of 800 pixels wide. Save and give the file the correct botanical name of the species in question.
We like to install a plug in for IrfanView - IrfanPaint. This gives us enough tools to touch up our images and add text over coloured blocks without opening a more sophisticated image editor like Photoshop or Gimp.
University of Melbourne Landscape Resources
A long list of various resources including online databases for landscapers.
Comparing the US system of plant zones with Australia's zones.