What does dicotyledonous mean?
Dicotyledonous is an adjective from botany describing any flowering plant whose embryo carries two seed leaves, called cotyledons. When such a seed germinates, these two leaves often emerge first and may even perform photosynthesis before the true leaves develop. The group includes most familiar broad-leaved plants — beans, sunflowers, roses, oaks, and maples among them — and stands in contrast to monocotyledonous plants such as grasses, lilies, and palms, which have only one seed leaf. Dicots typically also share other traits, including net-veined leaves, vascular tissue arranged in a ring, and floral parts usually in fours or fives. Although modern plant classification, guided by DNA evidence, no longer treats all dicotyledonous plants as a single formal taxonomic category, the word remains standard in biology teaching and scientific description. It is a formal, technical term, generally shortened to 'dicot' in casual conversation, and is essential vocabulary for anyone studying plant structure or evolution.
adjectiveOf a flowering plant: having an embryo with two seed leaves (cotyledons). Dicotyledonous plants form one of the two major groups of angiosperms, the other being the monocotyledonous plants.
- (Of a flowering plant) having an embryo bearing two cotyledons; belonging to the former group Dicotyledones of angiosperms.
"Beans, oaks, and roses are all dicotyledonous plants, sprouting with a pair of seed leaves when they germinate."
"Most familiar broad-leaved trees, such as maples and oaks, are dicotyledonous."
"The botanist sorted the seedlings into monocotyledonous and dicotyledonous groups by counting their first leaves."
Crack open a peanut and you're looking at a dicotyledonous embryo in action — those two halves are literally its pair of embryonic leaves.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dicotyledonous
Dicotyledonous derives from the New Latin Dicotyledones, built on Greek elements: di-, meaning 'two', and kotylēdōn, meaning 'cup-shaped hollow' or 'seed leaf', which itself entered Latin as cotyledon. The word was coined in the context of early modern botanical taxonomy to name plants whose embryos have a pair of cotyledons, and English adjectival use developed alongside it in the eighteenth and nineteenth centuries as systematic botany flourished. Its closest relatives in English — cotyledon, dicotyledon, and monocotyledon — share the same Greek root.
How dicotyledonous is actually used
A technical term used mainly in botany, biology education, and scientific writing rather than everyday speech. In informal contexts, the abbreviated forms 'dicot' (adjectivally 'dicot') are far more common. Modern classification systems based on molecular phylogenetics have largely abandoned the traditional 'dicotyledons' as a single formal taxonomic group, though the term remains widely used descriptively.
Easily confused with dicotyledonous
Monocotyledonous plants have only one seed leaf in their embryo (grasses, lilies, palms), whereas dicotyledonous plants have two.