monocotyledon

Monocotyledons, or monocots, are a major lineage of flowering plants (angiosperms) defined by having a single seed leaf, or cotyledon, in the seed. They include about 60,000 species across numerous families, such as Poaceae (grasses), Orchidaceae (orchids), Arecaceae (palms), Liliaceae (lilies), and Cyperaceae (sedges).

Key diagnostic features commonly associated with monocots include the presence of a single cotyledon; leaves with parallel venation; vascular bundles scattered through the stem cross-section rather than arranged in a ring; and a fibrous root system. Flowers are typically organized in parts of three, and pollen grains usually have one opening (monosulcate).

Most monocots are herbaceous; woody monocots are uncommon but include palms and some others, which lack true secondary growth produced by a vascular cambium. Many monocot seeds store nutrients in an endosperm, but in some species the endosperm is consumed during germination and the cotyledon becomes photosynthetic.

Economically important monocots include the major cereals—rice, wheat, maize, barley, and sorghum—as well as sugarcane and numerous forage grasses. Orchids, lilies, irises, and other ornamentals also belong to this group.

Taxonomically, monocots are a clade within the angiosperms. In modern classifications such as APG, they are treated as a distinct lineage (Monocots) comprising numerous orders and families, united by embryological and morphological traits rather than a single shared flower structure. The group is ecologically diverse and economically important.