What are cotyledons in a plant?

Cotyledons are the first leaves that develop from a seed during the early stages of a plant's growth. They serve as the initial source of nourishment for the plant embryo before it is able to photosynthesize on its own. Cotyledons vary in number and structure, with some plants having one cotyledon (monocots, like grasses) and others having two (dicots, like beans). This characteristic is vital for plant identification and classification, as well as understanding plant development.

The other choices refer to different parts of the plant. Roots anchor the plant and absorb nutrients and water from the soil, stem nodes are points along the plant stem where leaves or branches emerge, and flower petals are modified leaves that often attract pollinators. While all these options are essential to a plant's biology, they do not pertain to the definition of cotyledons.