tracheid

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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 ?
During Phase 3, once the lateral superficial layers and large tracheids of wood are filled, further penetration of liquids takes place via the bordered small-diameter pits and is therefore restricted by the size and polarity of the penetrating liquid.
Vessels move more water efficiently than do tracheids because the perforations in their end walls are larger than the tracheid's pits and because the cross-sectional area is much greater.
All samples were soaked in distilled water under vacuum for at least 48 h to refill embolized tracheids.
4J); however, two extremely weak growth interruptions characterised by diffuse zones of 12-18 [micro]m diameter tracheids are present (Figs.
ring-porous wood: Secondary xylem characterized by large vessels and tracheids being produced early in the season (following favorable growing conditions); each term of growth activity is seen as a ring.
All four genera possess an oblique vessel pattern as well as spiral thickenings in vessel members and tracheids.
Without knowing that Borya is a "resurrection plant" that grows on briefly moist granite shelves, one would be unable to understand the distinctive vessels and tracheids in its stems.
Pit membranes provide a pathway for the flow of water between tracheids in the xylem of vascular plants.
It is expected that as the tree matures, the proportion of latewood tracheids with thicker walls and higher SG increases compared with the initial stages of growth where thin-walled earlywood cells are predominant.
Bailey and his collaborators reasoned that the cell type antecedent to vessel elements was represented by tracheids and progressed via tracheid-like vessel elements to ones that were very different (Fig.
in open-ended tracheids formed by sawing (Smith and Purslow 1960, Marcovich et al.