Leaf blade
/ˈlif ˌbleɪd/
Definition
Leaf blade refers to the broad, usually flat part of a leaf, also called the lamina. It is the main photosynthetic surface, where most light capture and gas exchange occur through tiny pores called stomata. The leaf blade is distinct from the petiole, which is the stalk attaching the leaf to the stem, and from the midrib and veins, which support the blade and transport water and sugars within it.
Function in Plants
- Main site of photosynthesis: The leaf blade contains most of the chloroplast-rich tissue that captures light and turns carbon dioxide and water into sugars for growth and storage.
- Shape affects water and heat balance: Its size, thickness, and surface features influence how quickly a plant loses water, sheds heat, and copes with sun, wind, or dry air.
- Useful for plant identification: Margins, veins, lobes, texture, and tip shape on the leaf blade are key traits used to identify species and compare related plants.
- Can signal growing conditions: Changes such as scorch, yellowing between veins, spots, or curling on the leaf blade may point to stress from light, watering, nutrients, pests, or disease.
Related Terms
Leaf
Leaf refers to a plant organ, usually flat and green, that grows from the stem or a branch and is specialized for…
Leaflet
Leaflet refers to one of the individual blade-like sections of a compound leaf, where a single leaf is divided into…
Petiole
Petiole refers to the stalk that attaches a leaf blade to the stem. It is a plant structure found in many, but not all…
Midrib
Midrib refers to the main central vein of a leaf blade. It runs from the leaf stalk, or petiole, toward the tip and is…
Vein
Vein refers to one of the vascular strands in a leaf or other plant organ. It contains xylem and phloem, the tissues…
Venation
Venation refers to the pattern and arrangement of veins in a leaf blade, or sometimes in other flat plant organs. It is…
Leaf axil
Leaf axil refers to the upper angle formed where a leaf stalk or leaf base joins the stem. It is a plant structure and…