I had spent a number of hours yesterday scouring local nurseries and markets for potential material for the Landscape eWorkshop, when I came across this sad little Euc. The label on the 250mm post said "Euc. sideroxylon rosea" (Pink Flowering Red Iron Bark), and it was reduced to $10 (less 20% due to a sale). The material is largely unremarkable but for the beginnings of a nice, smoothly tapered lignotuber. The leaves are quite a nice shape and size for Bonsai styling.
The first thing I did once I got it home was to remove the thick layer of mud, sand and silt which had made its way into the pot. Along with the mud, I also removed quite a few weeds, including the particularly noxious Sagina: it appears that the layer of mud had prevented the roots of the weeds from getting down into the soil, which is a very good thing when dealing with something as nasty as Sagina. I continued to poke around the surface soil for some time, trying to locate the base of the lignotuber, and to determine if there were roots present close to the trunk. (In the past, I have encountered nursery Eucs on which the 'surface roots' were merely roots which had grown upwards from tap-style roots deep in the pot. When such roots are present, pruning the roots from the bottom up can mean that you rapidly end up with few or no feeder roots at all...

Before getting too far into the root-pruning, I cut back the dead portion at the top of the tree, as well as most of the new foliage. The pruning served two purposes in this case: it makes the tree much easier to handle during root-pruning and repotting; and, the reduction of the foliage is in keeping with the idea of balancing the leaves and roots. After I located the base of the lignotuber, I set about hacking off the lower part (about 50mm) of the roots with a small, sharp hatchet, after which I began to work my Stick Of Poking™ back up through the mess of roots. In the end, I had removed around 80% of the roots, including some (but not many) that were finger thick.

Once I was satisfied that I could not massacre the roots any further, I cut the base off the original pot and trimmed the edges flat. I then placed a few centimetres of my Bonsai mix into the bottom of a 250 x 150mm bulb pan, set the old pot base onto the soil, and wired the tree into place. (The purpose of the cut-off pot bottom is to prevent any new roots growing directly downward.) I then backfilled with my mix and watered thoroughly, which has caused the mix to settle in and compact somewhat. Just before I took the final photo, I topped up the soil to account for further compaction, and the 'finished' soil level is a lot higher than I expect it to be in future.
Thanks for your time, and I'll keep you all posted on any progress.
Fly.