What do leaves originate as?

Leaves originate as leaf primordia, which are small outgrowths that develop at the shoot apical meristem of a plant. During the early stages of development, these primordia differentiate into the various structures that form a mature leaf. This process involves the regulation of various genetic pathways and environmental signals that influence the growth and patterning of the leaf.

Leaf stipules, leaf blades, and leaf bases represent different structures within the overall leaf morphology, but they do not signify the initial stage of leaf formation. Stipules are protective structures that can be found at the base of some leaves, while leaf blades refer specifically to the flat part of the leaf that is primarily responsible for photosynthesis. The leaf base is the part of the leaf that attaches to the stem. Thus, while these other components are integral to the overall structure of a leaf, they do not represent the embryonic stage from which the leaf develops.