1. Forestry 280: Hardwood Anatomy
Hardwood Anatomical Structure
Longitudinal Cells
Ray Tissue
Distinction from Softwood
anatomy
Identifying characteristics
Forestry 280: Hardwood Anatomy

2. Forestry 280: Hardwood Anatomy
Longitudinal Cells
Fibers
Vessel Elements
Longitudinal Parenchyma
Tracheids
Forestry 280: Hardwood Anatomy

3. Forestry 280: Hardwood Anatomy
Fibers
Fiber Tracheids – long, tapered, thick walled
hardwood xylem cells
Similar to Softwood Tracheids:
Contain bordered pits
Secondary thickening of cell wall
Forestry 280: Hardwood Anatomy

4. Forestry 280: Hardwood Anatomy
Fibers
Distinction from Softwood Tracheids:
Shorter in length, 1 – 2 mm
Round in cross section
Almost solely responsible for strength
Libriform fibers – Similar to fiber tracheids
except for “apparent simple pits”
Forestry 280: Hardwood Anatomy

5. Forestry 280: Hardwood Anatomy
Vessel Elements
Vessel Elements – Specialized vertical conducting cells
Much larger in diameter than other longitudinal
hardwood cells
When viewed in cross section commonly
termed pores
Typically they do not elongate
These cells join vertically to form vessels
Vessels often stray from straight alignment
Forestry 280: Hardwood Anatomy

6. Forestry 280: Hardwood Anatomy
Vessel Elements
Wide range of pore diameters 20 – 300 µm
Variation often occurs within a growth ring:
Ring Porous – Early wood contains large vessels
late wood with smaller pores
Diffuse Porous – Fairly uniform pore diameter
throughout growth rings
Semi–ring–porous or semi–diffuse–porous
Forestry 280: Hardwood Anatomy

7. Forestry 280: Hardwood Anatomy
Vessel Elements
Perforation Plates: Cell divisions that contain unrestricted
voids or perforations that allow fluid transport
Perforations formed by enzymatic degradation of plates upon
maturation of the cells
Perforation plate patterns can
be use for species identification
purposes
Forestry 280: Hardwood Anatomy

8. Forestry 280: Hardwood Anatomy
Vessel Elements
Vessel Pitting:
Vessel to Vessel – Three typical arrangements (below)
Vessel to fibers or tracheids – Typically bordered
Vessels to parenchyma – Bordered, half-bordered, or simple
Forestry 280: Hardwood Anatomy

9. Forestry 280: Hardwood Anatomy
Vessel Elements
Tyloses: Outgrowths (or ingrowths!)
of parenchyma cell walls into the lumen
of adjacent vessel elements
Function: Primarily in damaged tissue
Protect against moisture loss
Prevent the spread of pathogens
Act as a barrier in the formation
of heartwood
Forestry 280: Hardwood Anatomy

10. Forestry 280: Hardwood Anatomy
Vessel Elements
Tyloses formation:
Enzymatic degradation of pit membranes between
parenchyma and vessel elements
Outgrowth of parenchyma cell membrane into vessel (Tylosis)
Tyloses may remain thin walled or experience secondary
thickening
Presence of tyloses can affect the utilization of wood
Forestry 280: Hardwood Anatomy

11. Forestry 280: Hardwood Anatomy
Longitudinal Parenchyma
Parenchyma are thin-walled storage cells
May have darkly-stained contents
May comprise 1-24% of wood volume (domestic hardwoods); may be up to 50% (some tropical species)
Forestry 280: Hardwood Anatomy

12. Forestry 280: Hardwood Anatomy
Longitudinal Parenchyma
Axial strand parenchyma – formed by transverse division
of fusiform cambial initial
Fusiform parenchyma – derived from fusiform cambial initial
tapered at both ends, storied
arrangement
Epithelial cells – surround gum canals or gum ducts,
typically traumatic in origin
Forestry 280: Hardwood Anatomy

13. Forestry 280: Hardwood Anatomy
Longitudinal Parenchyma
Parenchyma
Arrangement:
Forestry 280: Hardwood Anatomy

14. Forestry 280: Hardwood Anatomy
Hardwood Rays
Cell Types – Ray Parenchyma
Procumbent – horizontally oriented when viewed in radial plane
procumbent = “lying down”
rectangular cells in brick-like arrangement
typically found at the center of rays
Upright – vertically oriented when viewed in radial plane
sometimes called square ray cells
long axis of cell aligned vertically
Forestry 280: Hardwood Anatomy

15. Forestry 280: Hardwood Anatomy
Hardwood Rays
Ray types:
Homocellular – composed of a single
cell type; either procumbent or upright
Heterocellular – composed of both procumbent
and upright ray parenchyma cells
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Rays may be narrow (uniseriate), multiseriate,
wide “oak-type” (very wide multiseriate rays)
or aggregate
Forestry 280: Hardwood Anatomy