Some grass types are can nurture growth in plants. If they are confused or finding it hard to control themselves because of the spores it could be related.

Orrrrr, maybe the northern forest is just naturally full of weird plants and fungi. Could be either. Who knows.

[ definitely not them, who basically only just showed up in this world. who knows what's normal here. ]

What do you mean by strange, though? Just overgrown or something else?