Shyvanna's E, both the projectile and the scorched earth, are very misleading in terms of visuals. In my opinion, abilities should be visually representative of how much damage they deal. Shyvanna's E is even more subtle than Morgana's pool and Nasus' E, even though it frequently does more damage than either of those spells.
Shyvanna's E should look less a minor fracture on the ground, and more like an actively burning flame rising up from the ground. It looks even less potent when it's on uneven ground or in a bush.