It appears to be a poisoncounterpart to Sleep Powder and Stun Spore, as the Accuracy, Contest group, appeal, effects, Japanese names and animation are the same or very similar. They are also usually learned at the same level or in a similar pattern.
Bulbasaur releases a seed from the back of its bulb at the opponent. The seed then explodes around the opponent, releasing toxic spores into the air around it.