Forestry 280: Hardwood Anatomy 1 Hardwood Anatomical Structure • Longitudinal Cells • Ray Tissue • Distinction from Softwood anatomy • Identifying characteristics
Forestry 280: Hardwood Anatomy 1
Hardwood Anatomical Structure
• Longitudinal Cells
• Ray Tissue
• Distinction from Softwood anatomy
• Identifying characteristics
Forestry 280: Hardwood Anatomy 2
Longitudinal Cells
• Fibers
• Vessel Elements
•Longitudinal Parenchyma
• Tracheids
Forestry 280: Hardwood Anatomy 3
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
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 tracheidsexcept for “apparent simple pits”
Forestry 280: Hardwood Anatomy 5
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
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
Vessel Elements
Perforation Plates: Cell divisions that contain unrestricted voids or perforations that allow fluid transport
Perforations formed by enzymatic degradation of plates uponmaturation of the cells
Perforation plate patterns canbe use for species identification purposes
Forestry 280: Hardwood Anatomy 8
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
Vessel Elements
Tyloses: Outgrowths (or ingrowths!)of parenchyma cell walls into the lumenof 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
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
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
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 14
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
Hardwood Rays
Ray types:
Homocellular – composed of a singlecell type; either procumbent or upright
Heterocellular – composed of both procumbentand upright ray parenchyma cells**************Rays may be narrow (uniseriate), multiseriate,wide “oak-type” (very wide multiseriate rays)or aggregate