The right amount of water is essential to the life cycle of a plant. Too much or too little moisture can interfere with the plants ability to move and convert minerals and nutrients, causing stresses that invite diseases and insect pests. Water moves through the healthy plant continuously, transporting nutrients throughout the plant. The pressure of the water within the plant also gives it much of its physical support, a fact that becomes obvious when moisture-deprived plants wilt or droop. Water helps the plant maintain a healthy temperature as the moisture in the plant evaporates and cools both the plant and the air around it.
Anchoring the plant to the ground is the root system. It absorbs water and nutrients from the soil and carries them to the plant stem. The root system of the plant can be in the form of a taproot system or a fibrous root system. Either way, it is these roots that carry the water and nutrients that the plant needs to grow.
The plant stem carries water and nutrients to the leaves. The main responsibility of the movement of water in the stem falls to the xylem cells, while the phloem cells are responsible for moving the nutrients. Some water is moved through the phloem cells, along with the nutrients.
The main function of the leaves is to make food for the rest of the plant. Veins in a leaf carry water and nutrients within the leaf. The waxy covering on the leaf is the cuticle, and serves to protect the leaf and its functions.
The leaves of plants are attached to the plant by a petiole. Plant leaves can be either simple or compound. The simple leave is one leaf attached to a stem. A compound leave is a cluster of small leaves, or leaflets attached to the petiole.
While the leaves of the plant can absorb moisture from the air, except for succulents, plants depend on the moisture absorbed from the root system and delivered through the stem.
The flower is the part of the plant where reproduction happens. Water and nutrients carried through the stem from the root system and leaves to the embryo within the seed. The embryo holds all of the water and nutrients it needs to survive until it germinates and establishes a root system to start the process all over again.