Phloem / Inner Bark - Phloem or inner bark is located just outside the cambium zone and to the inside of the phellogen and the outer bark. The phloem cells are born by the cambium zone. It, the phloem, maintains a symplast. Phloem, or inner bark, is a transport tissue. It transports energy-containing substances made in leaves toward non-woody absorbing roots. Phloem is a transport tissue in vascular plants. Xylem rays connect radially to form phloem rays. The phloem rays connect circumferentially to form the phellogen. The phloem is made of sieve tubes and companion cells. We believe the sieve tubes are like toothpaste tubes and are squeezed by the companion cells moving materials towards the sink and or non-woody roots. Half truth - Phloem transports materials down. Some branches hang or grow downward thus the movement of materials would first be in an upward direction toward the trunk.
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