Leaf

Leaves are among the most important appendages of the plant because they carry out photosynthesis and also help remove excess water from the plant body through transpiration. A leaf develops from a leaf primordium and is a dorsiventrally flattened, lateral appendage of the stem, produced at the nodal region — that is, it shows exogenous origin. Every leaf's axil bears an axillary bud. Unlike the stem, a leaf shows limited growth and does not have an apical bud or a growing point of its own. The leaf is thin, expanded and green because of the photosynthetic pigments it contains.

Typical leaf structure. A typical leaf shows three main parts:

• Leaf base (hypopodium) — the point by which the leaf remains attached to the stem. The nature of the leaf base varies between plants; it may be pulvinus (swollen), sheathing, or ligulate. In some plants the leaf base bears a pair of lateral outgrowths called stipules — a leaf with stipules is stipulate, one without is exstipulate; stipules are normally green, protective structures.
• Petiole (mesopodium) — the part of the leaf that connects the lamina to the leaf base. A leaf with a petiole is petiolate, and one without a petiole is sessile. The petiole helps expose the lamina to light and also assists in conduction. …