Fig. 11.3-7. Transverse section of cactus stem (Gymnocalycium megatae; no common name). This cactus too has cortical bundles that carry sugars away from the outermost, chlorenchymatous cortex to the phloem of the stele. The cortical bundles also carry water from the stele xylem outward throughout the cortex, replacing the water that is lost by transpiration (even though cacti have very thick cuticles, they still lose water). The size of cortical bundles varies greatly from species to species; in this species, an entire cortical bundle is much smaller than ordinary cortex parenchyma cells.