If you swallow a watermelon seed or apple seed, a tree or plant will grow inside your stomach.
Seeds require specific conditions to germinate: proper soil, moisture, light, and temperature. Your stomach provides only a warm, acidic, dark environment where most seeds are broken down by digestive acids. Even if a seed survived, it would be excreted along with other digestive waste. The myth persists as a humorous way to encourage kids not to swallow seeds.
Reception
Sources
- Seeds and Digestion - Biology Online PRIMARY
- Snopes: Seed Tree in Stomach REFERENCE