that's an excellent question. i'm not really sure if dandelions would be able to withstand the humidity of most vivariums. they might. but i am 100% positive that a seedling or juvenile plant will not withstand the trampling that a bull frog would dish out. the only other concern i would have with them is that they dig very long and deep root structures, and i'm not sure how they would enjoy a shallow substrate that we keep in vivs.