Vein
/veɪn/
Definition
Vein refers to one of the vascular strands in a leaf or other plant organ. It contains xylem and phloem, the tissues that move water, minerals, and sugars, and it also helps support the blade. In leaves, veins form visible patterns such as parallel or netlike venation. A vein differs from the surrounding leaf tissue because it is a distinct transport and support structure rather than the main photosynthetic surface.
Function in Plants
- Transport network: A vein helps move water, minerals, and sugars through a leaf or other organ, linking photosynthetic tissue with the rest of the plant.
- Mechanical support: Its tissues also strengthen thin plant parts, helping leaves hold their shape and resist tearing, wilting, or collapse in wind and sun.
- Identification clues: The arrangement can be useful in plant identification. Parallel patterns are common in many monocots, while netlike patterns are typical of many dicots.
- Visible health signal: Changes in color between and along a vein can point to stress or nutrient problems, such as interveinal chlorosis, where tissue between them turns yellow first.