xylem
The tissue in vascular plants that transports mainly water and nutrients from the roots through the aerial part of the plant to the leaves and buds. Xylem occurs in localized vascular bundles in herbs and some species with ligneous stems. In plant species having secondary thickening these bundles coalesce to give a continuous cylinder of secondary xylem, or true wood.
This definition is abridged from A – Z of tree terms: A companion to British arboriculture.
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