What kind of plant is this

[Harlock]

Well, if by adverse you mean they grow like weeds and you have to prune them weekly, then yes, there are some adverse effects. Seriously, though, some plants can burn under high light, but I've only gotten that from hearsay and never experienced it first hand (and likely never will as my tank is medium light and tall).

 

[benedictj]

I can vouch for that Harlock. I have a jungle of overgrow Spiral Val that literally forms a canopy over a portion of 10g. If I don't trim it, the upper parts turn red from being to close to the PCs.