sugarcane
yes they do.
in the fruits
No, watermelons store food as sugar and nutrients in the flesh of the fruit, not in the stem. The stem primarily helps transport water and nutrients from the plant to the developing fruit.
The center of plant stem that can store food is called the pith. The pith has a spongy texture. The pith in a tree is called the trunk.
Leafless cactus plants
yes they do.
They store food in the roots
in the fruits
Plants that store food in their stems include succulents like cacti and desert plants, as well as tuberous plants like potatoes and sweet potatoes. These plants store energy in their stems to use during times of drought or when growing conditions are not favorable.
Plants store extra energy as starch, which can come in a wide range of forms. Potato plants store them in big underground tubers that we know as the edible vegetable, as do carrots, parsnips, turnips, etc. Apples, tomatoes, grapes and oranges are all other examples of energy storage sites. You may realise that these often correlate with the plant's seed location/vessel, for obvious reasons.
Stem
in its stem
Stem
Stem
A succulent and a cactus both store water in their spongy stem or leaves.
Plants store food for energy.
Sugarcane stores food in its stalks. The stalks contain a high concentration of sucrose, which is the primary source of energy for the plant. This stored sugar is used for growth and reproduction, as well as providing energy during times of stress.