Root

A root is a plant organ that anchors the plant and absorbs water and mineral nutrients from soil. It can also store resources and interact with soil organisms.

Root cap: A protective tissue covering the growing tip of a root. It shields the delicate root tip as it pushes through soil.
Primary root: The main root that develops from a seedling's embryonic root. It forms the central axis of many root systems.
Nitrogen fixation: The conversion of atmospheric nitrogen into biologically usable nitrogen compounds. Some roots host bacteria that supply plants with fixed nitrogen.
Plant hormone: A signaling molecule that regulates growth and development in plants. Hormones coordinate root branching, elongation, and responses to conditions.
Root hair: A fine extension of a root epidermal cell that increases absorptive surface area. Root hairs provide much of the surface used to absorb water and minerals.
Lateral root: A root that branches from another root. Lateral roots expand the volume of soil explored.
Root nodule: A specialized swelling on certain plant roots that houses nitrogen-fixing microorganisms. Nodules are the sites of symbiotic nitrogen fixation in legumes.
Gravitropism: Directional growth in response to gravity. Positive gravitropism guides many roots downward through soil.
Apical meristem: A region of actively dividing cells at a plant organ's growing tip. Cell division here drives root growth in length.
Taproot: A root system dominated by one large, deep-growing primary root. This architecture concentrates growth along a strong central root.

Linked from 18 pages