You can find aquarium plants at the following places:

Aqua art-Salwa Road-Al Ain Building opp to Tata Showroom
Golden Fish-Najma near to carpet center
Tropical Fish- Near Al MArkhiya Roundabout close to Mcdonalds
Al Buhaira-At Al Nasr near family food center
Fish world-Najma near Al Ahli Bank

Hope this helps.