Dicotyledonous

Dicotyledonous, or dicot, refers to flowering plants whose seeds typically contain two seed leaves, or cotyledons. The term arises from this feature and was traditionally used to distinguish a large group from monocotyledonous plants, which have one cotyledon. In modern taxonomy the two-cotyledon criterion is retained for many practical purposes, but the formal, clade-based distinction is now expressed as eudicots, a major lineage within angiosperms that includes most plants once called dicots. Some basal angiosperm lineages also have two cotyledons but are not closely related to eudicots.

Most dicots typically show net-like leaf venation, vascular bundles arranged in a ring in the stem, and usually a taproot system, though many have a fibrous root. Pollen grains often have three apertures (tricolpate) rather than a single pore, and floral organs are commonly in parts of four or five. Most dicots have two cotyledons in the seed and seed leaves that store or mobilize nutrients for germination.

Dicots include a wide range of trees, shrubs, and herbaceous plants, including legumes (Fabaceae), roses (Rosaceae), oaks and maples (Fagaceae, Acer), and many Asteraceae. They are distributed worldwide, occupying nearly all habitats.

The term dicotyledonous is still used informally to describe two-cotyledon plants, but it does not always map to a single clade in modern phylogenies.