tracheids Long, tapered cells with pitted walls that form a system of tubes in the xylem and carry water and solutes from the roots to the rest of the plant. One type of xylem cells.
Tracheids and vessel elements
In vascular plants, the xylem is the tissue that carries water up the root and stem. In trees, it constitutes wood; the word is derived from Greek ξύλον xúlon, "wood, timber".
Tracheids, longer, and narrower than most vessels, appear first in the fossil record. Vessels occur later. Tracheids have obliquely-angled endwalls cut across by bars.
four xylem vessels
a group of xylem tracheids.
both carry water and dissolved minerals up the stem.
In most plants, pitted tracheids function as the primary transport cells. The other type of tracheary element, besides the tracheid, is the vessel element. Vessel elements are joined by perforations into vessels.
ring-porous wood Secondary xylem characterized by larger vessels and tracheids being produced early in the season (or following favorable growing conditions). Thus each term of growth activity is seen as a ring.
secondary xylem
Tissue produced by vascular cambium and composed of both tracheids and vessel elements.
secondary palate
the roof of the mouth in vertebrates formed anteriorly by a bony projection of the upper jaw forms the hard palate.
 See also: Tissue, Xylem, Cells, Plant, Roots
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