Blade
/bleɪd/
Definition
Blade refers to the broad, flat part of a leaf, also called the lamina. It is the main surface attached to the petiole, or leaf stalk, or directly to the stem in leaves without a stalk. This part contains most of the leaf veins and much of the tissue that captures light, exchanges gases, and carries out photosynthesis. In grasses, blade usually means the long, narrow upper portion of the leaf above the sheath.
Function in Plants
- Main site of photosynthesis: In most leaves, the blade contains much of the chlorophyll-rich tissue that captures light and makes sugars through photosynthesis, so its size and exposure strongly influence energy production.
- Surface for gas exchange: Tiny pores called stomata are usually concentrated on the blade. They let carbon dioxide enter and water vapor exit, linking the blade to both growth and water loss.
- Useful clue for identification: Shape, margin, texture, venation, and how the blade attaches to the stalk are key traits in plant identification and classification, especially when flowers are absent.
- Indicator of growing conditions: Color changes, scorch, curling, spots, or unusual thickness on the blade can point to stress from drought, excess sun, nutrient imbalance, pests, or disease.
Related Terms
Leaf blade
Leaf blade refers to the broad, usually flat part of a leaf, also called the lamina. It is the main photosynthetic…
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…
Compound leaf
Compound leaf describes a leaf divided into separate leaflets attached to a single stalk, or petiole, rather than one…
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…