Plant I don't know

[CARNO]

So no one knows this plant

 

[BoomerXIV]

So no one knows this plant

Like what @kwi said, it could be ludwigia, or it could be a hygrophila, you should google these 2 species and looks which one the most identical with yours

 

[AdoraBelle Dearheart]

Looks like the ludwegia glandulosa I recently bought (this photo stolen from google images)

Gets a deep red with high light and CO2, more greenish red in low tech systems.

 

[CARNO]

I think that might be it thank u

 

[CARNO]

I had a look but I don't really think it might be but can ludwegia go in pea gravel

 

[AdoraBelle Dearheart]

Yes, you can put most any plant in pea gravel, as long as it isn't a rhizome plant like java fern or anubius. Just add root tabs and liquid ferts so they get all the nutrients they need.