In trees, where does the movement of sugar primarily occur?

The movement of sugar in trees primarily occurs in the phloem. Phloem is the vascular tissue responsible for transporting organic nutrients, particularly sugars produced during photosynthesis in the leaves, to various parts of the tree, including the roots, stems, and fruits. This process is essential for the tree's growth and metabolism because it distributes the energy and building blocks necessary for cellular functions and development.

In contrast, xylem primarily transports water and dissolved minerals from the roots to the rest of the tree, which is a different function from the transport of sugars. The roots, while crucial for water and nutrient uptake, do not play a direct role in the movement of sugars throughout the tree. Bark, which includes both the phloem and outer protective tissue, does not specifically refer to the sugar transport function, making it less relevant to the movement of sugars within the tree. Thus, phloem is the specific tissue associated with the transportation of sugars, confirming its role as the correct answer.