What is the history of this tree? Did you purchase it in this state or have you been growing it out for a few years? I ask because understanding how the tree grows will help with design decisions...
My experience with these is short thus far. My experience with plants and trees of various types is long...I'm transferring some general knowledge to how I expect these to grow based on experiences with similar species and growth habits.
I have several desmodium...none nearly as fat as this
I've only had them for a yearish. I don't claim to have a robust handle on how they grow...but I do have some observations and suspicions based on similar plants and what I've witnessed with mine thus far...and that desmodium are herbacious weeds in the wild here! Unifoliatum is one of the few desmodium that can be grown to have a trunk. I'd guess that's what yours is...I'd guess yours is a 10" pot from Wigerts. Mine were 4" pots from same...
In the right (wrong?) conditions, these things can grow 4" thorns! I have one with thorns so long that the thorns have their own thorns!
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Those thorns grew within weeks of me unboxing these. Under my "normal" conditions, the thorns are much smaller and barely noticeable except by touch
They are a weed...not a tree
Their growth pattern is long, thin, viney branches. I'm not sure those cut branches are going to heal over any time soon. I'm also not sure the new branches off those ends are going to thicken up to look like natural taper without growing the new leaders out quite long. I could be wrong on that...but that's how mine is growing so far. Assuming that's true...you're going to want to hide those cuts!
As you can see from some of your pictures, the branches have a natural tendency to weep...especially when young. Again, growth habit is a low laying weed and not an upright tree
They only get a few feet tall in nature unless they have something to climb.
They are prolific flowerers!
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But, I believe they only flower on new growth. I do NOT know that for a fact and a quick search found no references
But some of mine have flowered twice and only on the latest growth each time.
Given the curves in your trunk line and the "ugly" cut branch ends that may take a long time to "fade out" and look more natural, you might try a weeping cherry sort of look. Maybe with the canopy cascading off to one side of the trunk?
It's hard to tell from the pictures but I'd consider cutting the first main branch so there's one main trunk line up to a single origin for a canopy. That should give you some freedom to play with planting angles to get the canopy placed over the trunk in an interesting way. Then try and fill in the canopy with weeping branches...keeping in mind that you might need to cut them back hard after flowering to get new growth that will flower. Otherwise, the tree might get really leggy with flowers far from the trunk. I do not know how well they'll heal over large flush cuts. I suspect not well at all
Unless you're going to try planting them, I would pluck the seeds as soon as you can...they are a nuisance once they mature! They turn into velcro! They will stick to anything you are wearing! They aren't called "tick weed" or "begger's lice" for nothing