food storage in plants
Storage in swollen tap roots is common in biennials (plants that grow and store food one year and flower and die the next). The carrot is an excellent example. By digging up the carrots at the end of the growing season, humans make use of the food that would have gone to make the next year's growth.
Root tubers are found in dahlias and the lesser celandine, for example. They develop from tiny buds at the base of the plant. They swell as food is passed into them and remain in the ground after the aerial parts have died down. Each tuber and its bud can give rise to a new plant.
Underground stems are the most common storage organs. They vary in structure but differ from roots in the possession of scale leaves and buds. Rhizomes are horizontal underground stems and are found in irises and many grasses. They do not always store food but when they do they are quite thick. The potato is a stem-tuber – a swollen part of a stem that stores food. When detached from the rest of the plant, the potato acts as a reproductive body.
Corms and bulbs are both underground storage structures and are often confused. In corms, the food reserve is stored in the swollen stem, while in bulbs, swollen scale leaves or the swollen bases of the previous year's green leaves contain the food.
Seeds are, of course, supplied with food reserves that enable the young plant to establish itself until it can begin to manufacture its own food.
The most commonly stored food material is starch but sugars and proteins are also stored. Fats are frequently important reserves in seeds while the reserve of the date seed is mainly cellulose.
Related category• BOTANY
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