Is it ensure, insure, or assure?
|vessel element |
An elongated, water-conducting cell in xylem, one of the two kinds of tracheary elements. The cells die when mature, leaving only their lignified cell walls. They are stacked one on top of another in long columns, called vessels. Water flows unimpeded from cell to cell along these columns through perforations in the cell walls. Vessel elements are found only in angiosperms. Compare tracheid.