Plant sap

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"Sap" redirects here. For other uses see sap (disambiguation).

Sap exuding (gummosis) from the stem of a koa tree, probably in response to surface damage

Sap is the fluid carried inside the phloem of a plant, circulating to distribute food and water to various parts of the plant.

Gummosis is the formation of patches of a gummy substance on the surface of certain plants, particularly trees. This occurs when sap (technically a latex) oozes from wounds or cankers as a reaction to outside stimuli such as adverse weather conditions, infections, insect attacks, or other mechanical damage. In many species, the sticky nature of sap has the effect of plugging wounds and thus detering attacks by insects, bacteria and fungi.

Maple tree sap is the basic ingredient in maple syrup. The sap of the rubber tree is used to make latex, which is vulcanized to make rubber. Spruce gum is another tree sap that was used by Anishinaabe peoples in Canada for small quick repairs to wood articles. The sap was collected and used in its raw form. Chewed, it makes a good emergency deep woods survival food. Pine sap collection for the naval stores industry created the wealth that was a substantial part of the agricultural economy of the southeastern United States between the 1860s and 1960s.

Sap has also been helpful in preserving insects from the past. Many insects species have been trapped and then preserved in the sap of different types of trees. Years later, when the sap has hardened into amber, scientist can study the insects (and occasionally other types of organisms), that were preserved inside.

Other non-tree plants also have sap, such as euphorbias (including poinsettias) and milkweeds, although the word sap is commonly only used to refer to trees.

In some countries (e.g., Latvia) it is usual to collect the sap of birch trees for human consumption (the sap is extracted during spring and can be used fresh or fermented).