By: Tony Wang
Plants, like animals, are composed of several different organs, tissues, and cells, each with varying degrees of complexity. Each of these functional units help a plant do two things: stay alive and reproduce.
Let’s start with the most common plant organ: roots. A root is an organ that anchors a vascular plant into the soil, absorbs nutrients and water, and stores carbohydrates. Vascular plants are plants that have xylem and phloem. Vascular plants are able to grow higher than other plants due to the rigidity of their xylem cells. Furthermore, tall plants with large shoot masses generally have a taproot system, which consists of one main vertical root, better known as the taproot, which penetrates the soil deeply and helps prevent the plant from toppling.
Another plant organ is the stem. A stem is a plant organ bearing leaves and buds. Each stem consists of an alternating system of nodes and internodes. Nodes are the points at which leaves are attached to the stem, and internodes are the segments of stem between the nodes.
A stem’s chief function is to elongate and orientate the shoot in a way that maximizes the photosynthesis potential of the leaves. Another function of plant stems is to elevate the plant’s reproductive structures, which essentially means to facilitate the dispersal of pollen and fruit. Additionally, some green plant stems can perform a limited degree of photosynthesis.
Let’s now talk about leaves. In most vascular plants, the leaf is the organ primarily responsible for photosynthesis. In addition to this, leaves also intercept light, exchange gases with the atmosphere, dissipate heat, and defend the plant from herbivores and pathogens. Leaves consist of a flattened blade and a stalk, both of which joins the leaf to the stem at a node.