The Plant Factory has an Urchin primitive, that is basically a ball that attached ‘branches’ grow out of in all directions. Vladimir at G@P has a tutorial on making a ‘virus’ using one of these. Here’s the result. This seems to be affected by wind and I can’t work out how to turn that off for this primitive. Maybe you can’t.
There’s quite a good tutorial on Lynda, but about half way through he makes some change to the model he’s been working on without explaining very well (i.e. in a way that I can understand) exactly what he did. After that it’s very hard to follow. He has provided exercise files but one needs the top version of The Plant Factory to open other peoples files, and it costs $1000 more than the one have, with no obvious other benefits. Good for collaborative work in a studio I guess, and for following tutorials on Lynda, but I refrained from upgrading just so I could see what he actually did. Fortunately Vladimir Chopine has a comprehensive set of TPF tutorials. Finding training for these programs is the biggest hurdle. They’re not exactly intuitive.