When a tree is damaged, you might notice a sticky, often aromatic substance oozing from its bark. This material is commonly known as tree pitch. It serves as a natural response from the tree to various forms of external harm.
Understanding Tree Pitch
Tree pitch is a viscous, sticky substance, also known as resin, produced by trees, primarily conifers like pines, spruces, and firs. It has a distinct, often strong scent and can range in color from clear to amber or darker hues. Upon exposure to air, pitch gradually hardens, forming a protective seal.
The chemical makeup of tree pitch primarily consists of organic compounds. These include resins, which are solid or semi-solid, and volatile oils, often referred to as terpenes. Terpenes are hydrocarbons responsible for the characteristic aroma of many conifer trees. The combination of these components gives pitch its characteristic stickiness and its ability to solidify.
The Purpose of Tree Pitch
Tree pitch plays a specialized role in the tree’s natural defense and healing. When a tree sustains an injury, it secretes pitch to seal the wound. This rapid sealing action helps to prevent excessive water loss from the damaged area. It also acts as a physical barrier against external threats.
Beyond physical protection, pitch contains compounds that deter insects and fend off invading pathogens. The sticky nature of the pitch can trap insects, preventing them from further damaging the tree. Its chemical properties provide an antimicrobial effect, inhibiting the growth and spread of microorganisms that could cause disease.
Pitch vs. Sap: Key Differences
While both pitch and sap are fluids found in trees, they are fundamentally different in their composition and function. Sap is a fluid that circulates within the tree’s vascular system, similar to blood in animals. It is primarily composed of water, sugars, minerals, and hormones, transporting nutrients throughout the tree to support growth and metabolism. Sap moves through specialized tissues called xylem and phloem, flowing both upwards from the roots and downwards from the leaves.
In contrast, pitch, or resin, is a distinct substance that is not involved in the tree’s nutritional transport system. It is a hydrocarbon-based secretion, produced in specialized resin canals, primarily by coniferous trees. Unlike watery sap, pitch is thick, gooey, and becomes tacky upon exposure to air. Its main function is protective, serving as a defensive and healing agent against injuries and biological threats. Deciduous trees, which lose their leaves seasonally, typically produce sap but do not produce this defensive resin.