bladbladen

Bladbladen are the lamina or blade of a leaf, the broad, flat portion that carries out photosynthesis and is usually connected to the stem by the petiole. They are the principal surface of a leaf and are distinguished from other leaf parts such as the stem stalk (petiole) and the leaf base. The blade’s primary functions are capturing light for photosynthesis, exchanging gases, and regulating water loss through stomata.

Anatomically, the blade consists of an upper and lower epidermis with a mesophyll layer in between. The mesophyll typically includes palisade tissue rich in chloroplasts and a spongy tissue that facilitates gas movement. Stomata, often located on the underside, control the exchange of carbon dioxide, water vapor, and oxygen. Veins provide support and transport water, minerals, and sugars; the pattern of venation varies among plants and is a key taxonomic feature.

Leaves show considerable variation in blade morphology. Shapes range from lanceolate and ovate to cordate or entire and deeply lobed. Margins can be smooth (entire), toothed (serrate or dentate), or lobed. Venation is net-like in many dicots and parallel in many monocots. In some species the blade is simple, forming a single lamina, while in others the blade is divided into leaflets, forming compound leaves with a rachis and petiolules.

Developmentally, blades arise from leaf primordia at the shoot apical meristem and can be modified by environmental factors such as light, water, and nutrients. Blade morphology is a common focus in plant taxonomy and ecology, reflecting adaptations to habitat and function.