Looking closely at a leaf

A leaf is joined to the stem by a stalk called the petiole. The flat, green part is the lamina or leaf blade; it is wide and thin to catch as much sunlight as possible for making food. Running down the middle is the thick midrib, and from it branch smaller veins, which carry water into the leaf and food out of it and act like a skeleton to hold the lamina flat. The edge of the leaf is the margin, which may be smooth or toothed, and the pointed end is the apex.