According to Table 3-3 in that reference, sapwood water percentages are higher in conifers than in angiosperms, probably because at the time of harvesting, tracheids in conifer woods retain water, whereas in angiosperm woods, vessels empty and fibrous tissue (libriform fibers mostly) is less likely to contain water.
The secondary xylem consists of vessels, thin-walled ray cells and axial parenchyma, and occasional patches of libriform fibers, which are narrower than the vessels.
The last few cell rows of libriform wood fibres at the border of the annual rings are more strongly lignified than the weakly lignified libriform wood fibres of the early wood.
Studies carried out by Schwarze et al on some tree species show that parenchyma cells resists degradation by brown rot fungi, whereas the surrounding libriform wood fibres are strongly decayed .
, of moderately short length, fine diameter and thick walls.
Wood background of stems composed of thin-walled wide libriform
La madera presenta elementos de vaso extremadamente cortos con puntuaciones areoladas alternas y placa de perforacion simple, parenquima axial vasicentrico y en bandas confluentes, rayos uniseriados, extremadamente bajos y fino y fibras libriformes
fibers as well as vessels are storied in Peritoma (= Isomeris), which is a shrub with sufficient secondary xylem accumulation to show storying.
Las especies presentan porosidad difusa, puntuaciones areoladas alternas y placas simples, rayos numerosos, pequenos y finos; las fibras libriformes
, la mayoria cortas y de diametro fino; el material ergastico presente en forma de gomas, cristales de carbonato de calcio y silice.
The most useful application of "specialization" in the Major Trends papers refers to differentiation in the roles of tracheary elements from tracheids which support the plant and conduct water into separate support (fiber-tracheids, libriform
fibers) and conductive cells (vessel elements).
However, maple contains areas of libriform
fibers with large diameters that may influence the local SG and this may affect lateral and principal forces due to a density gradient.
For imperforate elements, is the Baileyan pattern of true tracheids transforming to fiber-tracheids and then to libriform
fibers the only transformation series, or is there evidence of other evolutionary patterns?