Petiole
/ˈpɛtiˌoʊl/
Definition
Petiole refers to the stalk that attaches a leaf blade to the stem. It is a plant structure found in many, but not all, leaves; leaves without one are called sessile. The petiole positions the blade for light and air movement and contains vascular tissue, the xylem and phloem that move water, minerals, and sugars between the leaf and the rest of the plant.
Function in Plants
- Blade positioning: By holding the leaf blade away from the stem, petiole placement helps reduce self-shading and can improve light capture for photosynthesis.
- Flexible movement: In many plants, the petiole bends in wind and rain, which can lower tearing and mechanical stress on the leaf blade.
- Transport link: Inside the petiole, vascular tissue carries water and minerals to the leaf and moves sugars produced by photosynthesis back to the rest of the plant.
- Identification clues: Length, thickness, hairs, color, and whether the petiole is winged or swollen can help distinguish species and describe leaf form in botany.
- Propagation and stress signs: A petiole is often checked during plant care because drooping, rot, lesions, or insect damage there can affect the whole leaf, and some houseplants can be propagated from leaf pieces that include it.
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…
Leaf blade
Leaf blade refers to the broad, usually flat part of a leaf, also called the lamina. It is the main photosynthetic…
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…
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…
Leaflet
Leaflet refers to one of the individual blade-like sections of a compound leaf, where a single leaf is divided into…
Stipule
Stipule refers to a small leaf-like or scale-like appendage at the base of a leaf stalk, where the leaf joins the stem…