veining

Veining is the pattern or network of vein-like structures observed in a range of natural materials and organisms. The term is used most often in botany and geology, where it describes distinct vascular patterns or mineral-filled features, but it can also refer to the vascular network in animals in a broader sense.

In botany, leaf venation or venation refers to the arrangement of veins within a leaf. Common patterns include parallel venation, found in many grasses; pinnate venation, with a main midrib and lateral branches; palmate venation, where several main veins radiate from a single point; and dichotomous venation, where veins repeatedly fork. Reticulate venation, a net-like pattern, is typical of many dicot leaves. Vein structure supports the leaf, provides a conduit for water, sugars, and nutrients, and can influence photosynthetic efficiency and mechanical stability. Environmental factors such as light, temperature, and water availability can affect vein development.

In geology, a vein is a sheet or seam of mineral material that fills fractures in rocks, typically formed by hydrothermal fluids depositing minerals as they move through rock cracks. Veins commonly consist of quartz, calcite, or sulfide minerals and can show fibrous, crystalline, or banded textures. Their orientation and cross-cutting relationships help geologists interpret the history of fluid flow and tectonic activity. Veins may host economically important ore deposits, including gold, silver, and copper.

In biology, veins are vessels of the circulatory system that return deoxygenated blood toward the heart, forming a complex network known as the venous system. Veining patterns thus span descriptive morphology in plants, structural geology, and anatomical circulation.