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
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).