Q. Which of the following is not a stem modification?
Answer: Tuber of Sweet-potato
Notes: A modified stem is a part of a plant with special features developed for special functions. Modified stems can be found either above or below ground. Above the ground are crowns, stolons, runners or spurs, while below the ground include; bulbs, corms, rhizomes, tubers and tendrils. Sweet potato is an example of a tuberous root not modified stem.