While these are realistically more likely to be a type of boulder from the engine side. it would still be the easiest to seed them as trees via #10. Picture them as large rounded rectangle slabs stacked up against each other like card houses - there's probably a way to pull that off with some nice shapes. The textures for the trees could be either plain white/gray or full-on playing cards (although that might make each "card" quite large).
While these are realistically more likely to be a type of boulder from the engine side. it would still be the easiest to seed them as trees via #10. Picture them as large rounded rectangle slabs stacked up against each other like card houses - there's probably a way to pull that off with some nice shapes. The textures for the trees could be either plain white/gray or full-on playing cards (although that might make each "card" quite large).