dicotyledon

Dicotyledons, commonly called dicots, are flowering plants whose seeds typically contain two embryonic leaves, or cotyledons. The term historically distinguished one of the two major angiosperm lineages, alongside monocots, and includes a wide range of plants from trees to herbs.

In modern plant systematics, the group “dicots” is not a formal clade. Most species once labeled dicots belong to the clade eudicots, which comprises the majority of flowering plants. Some lineages once called basal dicots (for example water lilies) lie outside eudicots. Thus “dicot” is largely a historical term rather than a precise evolutionary grouping.

Typical features include reticulate leaf venation, vascular bundles arranged in a ring in the stem, and usually a taproot system. Pollen commonly has three apertures (tricolpate) in many eudicots. Floral parts are often in multiples of four or five, though many exceptions occur; seeds store nutrients in two cotyledons.

Dicots are highly diverse, with tens to hundreds of thousands of species, and include families such as Fabaceae (legumes), Rosaceae (roses), Asteraceae (daisies), Brassicaceae (mustards), Solanaceae (nightshades), and Apiaceae (carrots and relatives). They inhabit a wide range of environments and include herbs, shrubs, and trees.

Economic and ecological significance is major, with many dicot crops providing food, fibers, oils, and timber, and many dicots forming essential components of ecosystems. In modern usage, eudicot is preferred for phylogeny, while dicot remains a common, historical term.