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| Transport of Food |
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| Food is manufactured in the form of carbohydrates (sucrose) in the leaves. Thus, food is transported as sucrose along phloem. From the leaves the prepared food has to be transported to the roots, the younger top regions of the plant, the flowers and fruits. Thus, the food has to move in not only downward but also upward direction. |
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| Phloem cells, as mentioned earlier, are living cells with cytoplasm which is continuous. Sucrose molecules in the leaves enter the phloem cells by active transport. There is a concentration of sucrose in the phloem of the leaves. This creates a positive potential in the leaf phloem tissue. The phloem in the other parts of the plant have negative potential as food is continuously being used without being manufactured. Thus sucrose moves from the region of positive potential to the region of negative potential along the concentration gradient. That is, the food moves from leaves, the region of synthesis to the other parts like the roots, young leaves, flowers and fruits, the regions of utilisation. |
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| A Part of the Phloem Tissue |
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| Other than sucrose, phloem also transports hormones (from the site of synthesis to the site of action) and some of the mineral ions (from the leaves about to fall to the other regions). |
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| The transport of soluble substances like the sugars, amino acids and hormones by the phloem is called translocation. |
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