Juureid

Juureid (Estonian for roots) are the underground organs of vascular plants that anchor the organism and absorb water and mineral nutrients from the soil. They may also store carbohydrates and serve as a reservoir for energy. The root system contributes to plant stability and interacts with soil microbiota, such as mycorrhizal fungi and nitrogen-fixing bacteria in legumes.

Anatomy: A typical root has a root cap that covers the growing tip, a meristematic zone, and an epidermis with root hairs that increase the surface area for uptake. The cortex lies between the epidermis and the endodermis, which contains the Casparian strip that regulates water and solute flow into the central vascular cylinder (stele). The stele contains xylem and phloem; in many dicots, xylem is arranged in a central star or cross, while monocots show a different arrangement. The pericycle gives rise to lateral roots.

Growth forms: Plants develop either a taproot system, with a dominant primary root (common in many dicots), or a fibrous root system, consisting of many roots of roughly equal size (typical of many monocots). Adventitious roots can arise from stems or leaves; some species also produce storage roots (for example, carrot, potato) and specialized roots such as pneumatophores in mangroves.

Ecology and function: Root architecture adapts to soil conditions and resource availability. Root hairs and mycorrhizal associations expand the effective absorptive area and nutrient uptake, especially for phosphorus. Deep or sprawling roots affect water access and soil stability, while root turnover contributes to soil organic matter.

Human relevance: In agriculture and horticulture, roots are central to crop yield and quality, as well as to soil health. Root diseases and pests can impair uptake; management includes crop rotation, proper irrigation, and soil protection.