This tree is a supportless and bulkier limbed remix of 'Swamp Tree' by Micahol from Thingverse: https://www.thingiverse.com/thing:4861749/files
I remixed the model so that it would:
I recommend adjusting the height between the trees when you print to give them some variety.
The base of the tree fits in a standard medium space and is relatively stable depending on how rambunctious your players are. That said I have a based version as well. The tree on the based version is slightly smaller (80% scale) so that the roots fit on the base.
I recommend the version without the base as it really is just as stable.
The author remixed this model.