 They also serve as anti-herbivory structures, as their irregular shape and hardness will increase wear on teeth as the herbivores chews.For example, they are responsible for the gritty texture in pears, and in winter bears

Unlike xylem (which is composed primarily of dead cells), the phloem is composed of still-living cells that transport sap.The sap is a water-based solution, but rich in sugars made by photosynthesis.