In its intial stage of growth it is identical to Nether Wart. On its second stage of growth it takes on a blue color.
Harvesting Terra Wart may yield either Terra Wart plants, Terra Wart Seed Bags, or both. Eating Terra Wart plants removes all negative effects (except blindness) of potions, beer, or rum (similar to the effect of drinking milk).
Terra Wart Growth Stages: