How does phloem tissue react during the shedding of bark?

During the shedding of bark, phloem tissue is typically sloughed off along with the outer layers of bark. The phloem is responsible for the transport of nutrients, especially photosynthates, from the leaves to other parts of the plant. As the outer layers of the tree bark become old and are naturally discarded, so too does the phloem that is located just beneath the bark layer. This shedding process is a normal aspect of tree growth and helps in the rejuvenation of the tree's outer protection.

In contrast, the other reactions indicated in the choices do not typically occur during bark shedding. Phloem does not remain intact, as it is part of the layers that are being discarded. There is also no thickening of the phloem tissue during this process, as the tree is shedding old tissue rather than increasing it. Similarly, while there may be changes to color associated with the outer bark, this pertains more to the overall appearance of the tree rather than a specific change within the phloem itself. Thus, the correct understanding aligns with the functional role of phloem during bark shedding.