leafparts

Leafparts refer to the anatomical components of a leaf, the plant organ specialized for photosynthesis and transpiration. A typical leaf consists of a blade (lamina) attached to the stem by a petiole; some leaves are sessile. In many plants, a compound leaf has a rachis bearing leaflets.

Blade or lamina: the broad, flat surface where light is absorbed. Margins vary among species (entire, serrate, lobed). The internal tissue includes mesophyll arranged as palisade and spongy layers, and veins that provide support and transport.

Veins and venation: the midrib is the main vein, with secondary veins forming a network. Venation patterns—pinnate, palmate, or parallel—are diagnostic and affect mechanical strength and water movement.

Petiole, base, and pulvini: the stalk that attaches blade to the stem; the base may bear stipules, small appendages. Some leaves have pulvini at the base enabling movement in response to light and touch.

Epidermis and surface features: the outer epidermis is coated with a cuticle; stomata regulate gas exchange and transpiration, guarded by guard cells. Trichomes or other structures may deter herbivores or reduce water loss.

Specializations in compound leaves: a rachis extends the petiole and bears leaflets; some leaves possess tendrils, spines, or bracts as modified parts.