Sap Sap Sap is a fluid transported in xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is distinct from latex, resin, or cell sap; it is a separate substance, separately produced, and with different components and functions. Saps may be broadly divided into two types: xylem sap and phloem sap. Xylem sap (pronounced ) consists primarily of a watery solution of hormones, mineral elements and other nutrients. Transport of sap in xylem is characterized by movement from the roots toward the leaves. Over the past
Plant defense against herbivory of phenolics and tannins. Many plants have external structural defenses that discourage herbivory. Depending on the herbivore's physical characteristics (i.e. size and defensive armor), plant structural defenses on stems and leaves can deter, injure, or kill the grazer. Some defensive compounds are produced internally but are released onto the plant's surface; for example, resins, lignins, silica, and wax cover the epidermis of terrestrial plants and alter the texture of the plant tissue. The leaves of holly plants, for instance, are very smooth and slippery making feeding difficult. Some plants produce gummosis or sap that traps insects. A plant's leaves and