dicotyledonae

Dicotyledonae, commonly called dicots, are a historically defined group of flowering plants that typically possess two cotyledons in the seed. In classical botany they formed one of the two major divisions of angiosperms, alongside monocots. In contemporary classifications, the term dicotyledonae is largely informal and not treated as a single monophyletic clade. Most plants once placed in dicots belong to the clade eudicots, while monocots remain a separate lineage; a few early-diverging angiosperm lineages lie outside the eudicots.

Key characteristics traditionally associated with dicots include two seed leaves (cotyledons), net-like leaf venation, and vascular bundles arranged in a ring in the stem. Pollen typically has three apertures in many lineages, and floral parts are often in multiples of four or five, though there are numerous exceptions. Other features vary widely across the diverse group.

Diversity and examples: Dicots account for a large majority of flowering plants, with well over 200,000 described species spanning herbs, shrubs, and trees. They encompass many economically important families and genera, such as Rosaceae (roses), Fabaceae (legumes), Asteraceae (sunflowers), Brassicaceae (mustards), and numerous fruit crops, ornamental plants, and forest trees.

Evolution and systematics: Fossil evidence for dicot-like plants appears in the Early Cretaceous, with diversification continuing through the Cretaceous and Cenozoic. In modern systems such as APG IV, dicotyledonae is not recognized as a formal clade; the largest monophyletic group within what was once called dicots is the eudicots.