absorbing roots

Fine roots without secondary thickening or suberin at the extremities of the root system, responsible for the absorption of mineral nutrients and water. Microscopic root hairs (outgrowths from cells of the epidermis) arise close to the root tip, which increase the surface area for absorption. Absorbing roots are pale in colour, usually less than 1mm in diameter and physically delicate. They can arise at any depth but are concentrated close to the soil surface, in that part of the soil with high soil organic matter content and good soil structure (hence a good supply of nutrients and good soil aeration).

This definition is abridged from A – Z of tree terms: A companion to British arboriculture.
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