Answer:
underground stem -- for storage of food ex. potato , ginger.
spines for protection ex. citrus , bougainvillea
Explanation:
Rhizomes and corms are underground stems, modified for the storage of food. Also, these stems help in vegetative reproduction of these plants. The tips of the underground stem in potato plants become swollen due to the accumulation of food. The potato is a tuber that helps in the storage of food and bears eyes on it.
