Food Storage
 Food produced by the leaves in the growing season passes downward and is stored
in roots
Importance of Food storage in organisms.
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Overcomes the need for continuous food intake (heterotrophs) or food manufacture
(autotrophs).
Provides food reserves for periods of food scarcity (heterotrophs) and drought or
low temperatures (autotrophs).
Provides food reserves for special function, e.g. production of reproductive
structures, development of embryos.
Food substances and their function.
Carbohydrates: Mainsource of energy
Proteins: Helps in repairing damaged tissues and human growth.
Fats and oils: For vitamin absorption, insulation and source of energy
Minerals and Vitamins:
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Essential for the maintenance of good health
Control metabolism
Prevent diseases
 They can be distinguished from stem tubers because they lack buds and scale leaves
 There are 2 types of vegetative root storage
 Root tubers e.g. sweet potato, cassava
 Tap root e.g. carrot, radish turnip, beetroot
Site- Roots
Root Tubers
 Sweet potato (Ipomoea batatas) and cassava (Manihot esculenta) both store starch
and very small amounts of protein
 Sweet potato also stores maltose sugar
Tap Root
 A swollen tap root is the main root in carrot, radish turnip and beetroot, grows
vertically downwards
 Carrots store glucose in the phloem and is rich in vitamin A
Site: Stems
1. Stem Tubers
 Swollen underground stem
 Possesses scale leaves or leaf scars (which distinguish them from root tubers)
 The scale leaves have buds in the axils (called eyes)
 These buds can grow into shoots utilizing the stored food in the tuber
 Examples include:
 Yam (Dioscorea)
 Irish potato (Solanum) - mainly stores starch
2. Rhizomes
 Swollen, horizontal growing underground stem
 Has nodes at which scale leaves and axillary buds are present
 A terminal bud is present at one end
 Adventitious and contractile roots grow from the rhizome
 Examples include:
 Canna lily
 Ginger (Zingiber),
 Stores starch and oils (gives characteristic smell)
3. Corms
 Short, swollen underground stem
 Grows vertically
 Covered by scale leaves which grow from nodes
 Buds are present in the axils of the leaf bases
 Adventitious and contractile roots arise from the base of the corm
 A terminal bud is found at the top
 Examples include:
 Dasheen (Colocasia), cocoyam which both store starch
Site: Leaves
Bulbs
 All plants store food temporarily in their leaves
 Most store starch
 Onions chives (escallion) store sugar
 Some plants develop underground storage organs of swollen leaves which are called
bulbs
 Storage leaves grow from a flattened stem and are enclosed by dry, scaly outer
leaves.
 The stem bears adventitious roots
 Tiny lateral buds are found in the axils of some of the storage leaves
 SEEDS
 Provide food for young developing embryos for early growth
 Young plants are unable to make their own food until they form green leaves
and are able to photosynthesize
 FRUITS
 Food reserves in fruits are important for attracting animals which disperse
their seeds.
Fruits and seeds contain varying amounts of carbohydrates, fats, proteins, vitamins,
minerals and water.