Hydroid (botany)

In botany, a hydroid refers to the water-conducting cells in certain mosses and related bryophytes. These cells are structurally simpler than the xylem found in vascular plants, lacking the complex cell wall thickenings associated with true tracheids or vessel elements. Hydroids primarily function in the transport of water throughout the plant body, facilitating nutrient distribution and overall hydration. They are elongated cells that are often dead at maturity, leaving a hollow lumen for water to flow through. The presence and arrangement of hydroids contribute to the structural support and water relations of non-vascular plants, enabling them to colonize diverse terrestrial habitats. Hydroids are considered an evolutionary precursor to the more complex water-conducting tissues found in vascular plants.