Short answer: peanuts are eaten by many Jains even though the pods grow underground, because in Jain dietary norms peanuts are treated differently from true “root vegetables.”

• What groundnut is: A peanut is a legume. The plant flowers above ground, but the pod develops underground and is harvested from the soil. It’s technically not a root vegetable like potato or onion.
• Jain principle behind eating it: Jainism emphasizes non-violence (ahimsa) toward all living beings. Many Jains avoid eating true root vegetables because uprooting them can kill underground life. Peanuts, being seeds/legumes stored in pods, are not classified the same way as roots; many Jains consider them acceptable.
• Differences between Digambar and Śvetāmbar: Dietary rules can vary by tradition and community. Some groups may avoid peanuts or certain other plant foods for karmic reasons, while others permit them.

If you’d like, I can point you to specific Jain texts or community guides that discuss “root vegetables vs. seeds” and how peanuts are viewed in different Jain traditions.