Possible Clues:

• Bread seed
• Rye-bread seed
• Plant making wheels on someone else's ground
• Seed source
• Plant with aromatic fruits, the seeds of which are used as a tonic or condiment
• Source of some seeds
• Seed cake — top half not yet cooked? That's right
• Garage empty? It has a pungent smell
• Seed used in sauerkraut
• Transport route blocked by a plant