Roots or mould? It doesn't matter.

Where there's water enough for plants, there's water enough for mould.

You can see the water damage to the paint and drywall along the baseboard and the bottom of the wall.

If you remove the baseboard, you'll likely see lots of mould.

Unfortunately, virtually all finished basements are done in ways that encourage mould growth and there are no easy cures.

Here is a link that might be useful: Inspectapedia: Mould Cleanup

did you figure this out? I have something similar on a spot of my subfloor when we took up old flooring to replace.

Hey Amanda, any luck figuring out what this is? I just pulled up some flooring in my basement and those tiny roots are everywhere.

I ripped off the drywall and theres definitely mold behind it, this area backs a shower. There's also more of these "roots", I did a bit of research and it looks like it could be a type of wet rot called "cellar fungus". I'm going to remove all of the affected drywall, re-do the shower and install a better exhaust fan!

Don`t know the exact english word - but it could also be the "Echter Hausschwamm"- google says "Real dry rot"