For plants, a basic set of structures include roots, stems and leaves. Usually all plants have these, and their beginnings are already formed inside the seed. All other organs, like spikes, tubers and tendrils, are specialized later from the basic structures. Let’s look at the basic structures a bit closer!
Roots are well branched because their job is to anchor the plant to the ground and absorb water and nutrients. Roots grow from their tips, where the cells divide and expand. The tip is covered with a root cap, which protects the “growing point” (aka apical meristem) and senses gravity, thus leading the root growth downwards. Some parts of the roots are covered with root hairs, which make the roots look fuzzy (see picture below). The root hairs take up water and nutrients very efficiently because they cover a huge surface due to their density. In the areas of the roots, where the root hairs are aged and not working, the roots start to branch again and again. The roots find their way to favourable areas by following gravity, humidity and oxygen and nutrient levels. The root system becomes well branched only in good conditions. The surface of the roots is often estimated to be five times larger than the surface of the plant parts above soil. An individual plant of an ordinary cereal crop may have tens of kilometres of roots, when all the branches are counted together. Some plants have very specialized roots: just look at a carrot or a red beet!
Further reading: Interesting article “The Rhizosphere – Roots, Soil and Everything In Between”
Roots become well branched in hydroponics.
The purpose of the stem is to elevate the plant above the soil, so the leaves can reach the light and the flowers are available for pollinators. The stem also takes care of food and water transportation between the roots and the leaves. A node is the place where a leaf is attached to the stem. Internode is the space between two nodes. The stem grows from its tip, known also as the terminal bud. If it’s destroyed, the plant will execute the plan B. Each node has points of growth (lateral buds) where the plant can start growing new branches. These buds are dormant until the terminal bud is destroyed. This is why gardeners want to prune their herbs: when you pinch off the top of the shoot, the plant will start to branch, becoming more bushy. This means you will get more leaves to harvest!
Read how to prune your herbs here.
The job of the leaves is to photosynthesize and to evaporate. The petiole supports the leaf and keeps it in an appropriate place for receiving light. Inside the leaf there are leaf veins, that support the leaf and transport water and nutrients. The first leaves (cotyledons) are already formed inside the seed. Often the cotyledons have a different form than the leaves that develop after them, known as foliage leaves or true leaves (see picture below).
Some plants have a very short stem, then all the leaves are close to each other, forming a rosette. These plants don’t need pruning, you can just harvest the leaves with the petioles. These plants include all the Fast Growers in Plantui selection, and also Coriander, Wild Rocket, Parsley, Bloody Sorrel and Violas.
Read more about the miracle of photosynthesis here.