Tracheids are a kind of water-conducting cell which can be found in any kind of land plant. They are the only type of water-conducting cell present in most bryophytes and gymnosperms.
Tracheids appear as long, thin cells which taper off at both ends. The secondary cell walls are perforated by pits; water travels through tracheids by traveling through pits which are lined up to intersect between cells. These pits have a pit membrane between them which prevent embolisms from traveling and rupturing the cell.
Tracheids are less efficient than vessel elements. However, they are the only water-conducting cells with pit membranes, meaning they are less susceptible to destruction via embolisms.