A summary of the evidence for translocation in phloem is listed below:1. When phloem is cut a solution of organic molecules flow out.2. Plants provided with radioactively labelled carbon dioxide can be shown to have radioactive carbon in the phloem after a short time.3. Aphids can be used to extract phloem sap. The content of the phloem sap shows that the daily fluctuation of sucrose content of leaves is mirrored by the sucrose content of phloem.
4. The removal of a ring of phloem leads to the accumulation of sugars above the ring and no sugar below the ring.
4. The removal of a ring of phloem leads to the accumulation of sugars above the ring and no sugar below the ring.