Anatomy and Ultra structure of softwood and hardwood

1. Anatomical differences of
softwood and hardwood
Group: 01
Students ID: MS-150501,MS-150509,MS-150510,MS-150512

2. Definition of wood
• Wood is a complex biological structure, a composite of
many chemistries and cell types acting together to
serve the needs of a living plant.
• It is a three dimensional, anisotropic and hygroscopic
raw material which mainly composed of cellulose
hemicelluloses and lignin.

3. Types of Wood
Hardwood:
• Hardwoods are not all have hard, heavy
wood, that come from angiosperms
(flowering plants).
• They are typically broadleaf, deciduous
trees such as maple (Acer), birch (Betula),
and oak (Quercus).
Softwood:
• Softwoods are not all soft, lightweight
wood. They are those woods that come
from gymnosperms (mostly conifers).
• They are generally needle-leaved evergreen
trees such as pine (Pinus) and spruce
(Picea)

4. Vessels (Pores)
When viewed from the endgrain, vessels simply appear to be
holes in the wood—what are commonly referred to as pores.
In a live tree, vessels serve as the pipelines within the trunk,
transporting sap within the tree. Vessel elements are the largest
type of cells, and unlike the other hardwood cell types, they can
be viewed individually—oftentimes even without any sort of
magnification.
Anatomy of Hardwood

5. Parenchyma
Parenchyma cells are thin-walled storage units. In hardwoods,
parenchyma is long, tapered longitudinal cells, brick shaped
epithelium around gum canals, and ray cells.
Anatomy of Hardwood (cont’d)

6. Apotracheal parenchyma Paratracheal parenchyma Banded parenchyma
Parenchyma types
Anatomy of Hardwood (cont’d)

7. • In Hardwoods, Rays
may be:
– Uniserate – one cell
wide
– Biserate – two cells
wide
– Multi-serate – many
cells wide.
• Ray width varies
between and within
species.
Rays
Multiseriate ray Uniseriate ray
Anatomy of Hardwood (cont’d)

8. Procumbent ray: In radial
view, procumbent ray cells
are elongated horizontally.
Upright ray: Upright ray
cells are either squarish or
vertically oriented
Anatomy of Hardwood (cont’d)
Rays

9. • Saclike or cystlike structures that
sometimes develop in a vessel and
rarely in a fiber through the
proliferation of the protoplast of a
parenchyma cell through a pit pair.
• They commonly form in hardwoods as
a result of wounding and effectively act
to prevent water loss from the area
around damaged tissues.
• They may also develop as a result of
infection from fungi or bacteria, again
to prevent water loss.
Anatomy of Hardwood (cont’d)
Tyloses

10. • In a living tree, hardwood fibers
have strong, thick cell walls that
mainly serve to support and
strengthen the trunk.
• When viewed from the endgrain,
fibers are very small and can’t be
seen individually.
• Instead, fibers can only be
distinguished in a broader sense
as colored areas which form the
backdrop of the wood’s
endgrain.
Anatomy of Hardwood (cont’d)
Fibers

11. Tracheid
• Tracheids are long cells
that are often more than
100 times longer (1 to 10
mm) than wide and they
are the major component
of softwoods, making up
over 90% of the volume of
the wood.
Anatomy of Softwood
• They serve both the
conductive and mechanical
needs of softwoods.

12. Anatomy of Softwood (cont’d)
• Much like tracheids, parenchyma are oriented along the
length of the tree-trunk, and are sometimes referred to as
longitudinal or axial parenchyma.
• Axial parenchyma cells are similar in size and shape to ray
parenchyma cells, but they are vertically oriented and
stacked one on top of the other to form a parenchyma strand.
Parenchyma

13. • With the exception of special fusiform rays, which occur in
conjunction with resin canals, regular softwood rays are
usually only one to two cells wide.
Anatomy of Softwood (cont’d)
Rays
• Because these normal rays
are much narrower, and lack
unique characteristics that
are observable with a 10x
hand lens, their usefulness in
identification is essentially
limited to microscopic
examination.

14. • Resin canals, sometimes referred to as resin
ducts, are unique to conifers.
• They are technically not individual cells, but are
actually open, tube-like spaces bordered by
special cells that have the ability to secrete pitch
or resin into the neighboring opening (canal).
• One of the apparent purposes of these ducts is to
protect and seal up a wound by exuding resin to
cover the damaged area of the tree.
• Accordingly, in rare instances, some softwood
species that don’t normally have resin ducts will
develop them as a result of trauma.
Anatomy of Softwood (cont’d)
Resin Canals

15. Anatomy of Softwood (cont’d)
Resin Canals

16. 1. Bowyer, J.; Shmulsky, R.; Haygreen, J.G. 2003. Forest products and
wood science: an introduction. 4th ed. Iowa City, IA: Iowa State Press.
554 p.
2. Desch, H. E., & Dinwoodie, J. M. (1996). Timber structure, properties,
conversion and use (No. Ed. 7). MacMillan Press Ltd.
3. Ross, R. J. (2010). Wood handbook: wood as an engineering material.
4. Brunner, I.; Brodbeck, S.; Buchler, U.; Sperisen, C. 2001. Molecular
identification of fine roots from trees from the Alps: reliable and fast
DNA extraction and PCR-RFLP analyses of plastid DNA. Molecular
Ecology. 10: 2079–2087.
5. Brunner, M.; Kucera, L.J.; Zürcher, E. 1994. Major timber trees of
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Forest Service, Pacific Forestry Centre. 1999.
References