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Definition

noun, plural: dicotyledons

A group of flowering plants belonging to the class Magnoliopsida of Angiospermae (angiosperms), characterized by having two photosynthetic cotyledons in the seed that may emerge from the ground when the seed germinates.

Supplement

Examples of dicotyledonous plants are beans, buttercups, oaks, sunflowers, etc.

The angiosperms (the flowering plants) can either be a monocotyledon (or monocot) or a dicotyledon (or dicot) according to the number of cotyledons in their seeds (which in the case of dicots the cotyledons are two, hence the name). The cotyledons of the dicots may also emerge and show above the ground and function similar to leaves (i.e. perform photosynthesis).

Apart from the number of cotyledons, other identifying characteristics are as follows:

• the number of flower parts - dicot flowers are tetramerous or pentamerous (in multiples of four or five)
• the number of pores in pollen - dicots have three
• arrangement of vascular bundles in the stem - in dicots, the vascular bundles are in concentric circles
• secondary growth - dicot stems usually have secondary growth
• the roots - dicot roots have taproot system
• the arrangements of major leaf veins - in dicots, the leaves have reticulate venation

Word origin: From di- ("two") + cot- from the abbreviation of cotyledon ("embryonic leaf").

Variant: dicotyledon

Compare: monocot