lecture 11 Flashcards
axial vs radial system
axial system: cells oriented with their long axes parallel to the long axis of the stem
radial system: cells which are oriented at right angles to the axis of the stem (perpendicular to the axial system)
what are the three planes for observing wood anatomy?
radial cut, transverse cut, and tangential cut
what makes up the anatomy of a tree trunk?
heartwood, sapwood, outer bark, inner bark
what is heartwood?
non-conductive wood that accumulates coloured metabolites/resins and functions in storage and defense (darker coloured portion, interior to sapwood)
what is sapwood?
actively conducting portion of wood with xylem parenchyma cells that are still alive (lighter coloured portion)
what is the outer bark?
all the dead stuff; cork cells and residual epidermis
what is the inner bark?
all the living stuff; cork cambium, phelloderm, cortex, phloem
what is the periderm?
mix of dead and living stuff; cork cambium and its derivatives (cork and phelloderm)
how are growth rings formed?
formed as a result of seasonal slowing/cessation of vascular cambium
patterns within a growth ring
- can be a gradual reduction in diameter of tracheary elements from early wood to late wood
- early wood forms at the beginning of a growth phase (i.e. spring)
- late wood forms after
what are the characteristics of softwood?
- generally are needle-leaved evergreen trees (gymnosperms) such as pine and spruce
- simple
- axial system: mostly tracheids “non-porous”
- radial system: ray parenchyma cells
what are the characteristics of hardwood?
- typically broadleaf deciduous trees (angiosperms) such as maple, birch, and oak
- complex
- axial system: tracheids and vessel elements “porous”
- radial system: ray parenchyma cells, more variety in size and shape
