Indian tobacco, (species Lobelia inflata), annual plant of the family Campanulaceae, native to open woodlands of North America. It was once considered a medicinal plant because of the emetic alkaloid present in the plant parts, especially the roots, but is now regarded as poisonous.
The Indian tobacco’s leafy flower spike, about 1 metre (3 feet) tall, begins blooming at the bottom and at maturity produces inflated, oval fruits. Its flowers are small, pale blue, and bilaterally symmetrical. Basal leaves are toothed and broadly oval; stem leaves are narrower. The plant is a lawn weed in some areas.