tracheid


Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.
Tracheidclick for a larger image
Fig. 299 Tracheid . General structure.

tracheid

any of several structures found in XYLEM, consisting of a cell which is long, slender and tapered with heavily lignified walls surrounding an empty lumen, the protoplasm having died.

The wall thickening can be continuous with BORDERED PITS, or else arranged in a variety of patterns, annular, helical and ladder-like. See Fig. 299 . Tracheids form the water-conducting tissues of GYMNOSPERMS, but are found also amongst the xylem vessels of ANGIOSPERMS

References in periodicals archive ?
Hypothesis: Although in angiosperms at large the tracheid may have been the ancestral imperforate tracheary element type, the phylogeny of Brassicales (Fig.
Lignin appeared to be completely removed from the cell corner middle lamella regions, but tracheids were still joined in other parts of the middle lamella.
We assume that the cumulated AE energy is a more reliable measure for PLC than the AE number per se, because the hydraulic conductivity is proportional to the 4th power of the radius of a capillary (Hagen-Poiseuille equation) and tracheid diameters are variable within a wood specimen.
Water moves through the xylem via vessel elements and tracheids in angiosperms and tracheids in the gymnosperms.
The liquid water in the tracheids is under tension, caused by transpiration from the needles.
Fahn (1954) rejected the passage of India ink particles through a perforation plate as an aid in deciding whether a cell is a vessel element or a tracheid.
in open-ended tracheids formed by sawing (Smith and Purslow 1960, Marcovich et al.
Vessels prominently dimorphic, the smaller ones grading into vasicentric tracheids.
Abbreviations used in the figures of this study: A = aperture; AP = appressorium; B = pit border; F = fiber; H = hyphae; L = lipid bodies; M = margo of pit membrane; P = parenchyma cell; PA = perforation in end wall of vessel element; T = torus; VT = vascular tracheid.
Biostructured phytoclasts showing internal structure are also detected and described as brown phytoclasts derived from tracheid tissues (Fig.
TABLE 4 Fiber or tracheid and ray parenchyma characteristics of species that are endangered or considered to be in threat of extinction in Costa Rica Spcies Fibers or tracheids FL LD WCT FC Anthodiscus chocoensis 1.
The tangential section displays uniseriate tracheid pits, homocellular rays and spiral thickenings (SCHWEINGRUBER, 1990).