Anatomy of wood

1. I S H A N V I N AY S H A H
C 0 0 6
4 0 5 0 4 2 1 0 0 0 7
M S C . I I
PA P E R 1

2. I N T R O D U C T I O N

3. • Wood is a porous three-dimensional, hydroscopic, interconnecting matrix
of cellulose, hemicelluloses and lignin.
• CONTENTS
A. Wood anatomy: Coniferous and angiosperm wood
B. Parenchyma: storied and non-storied wood parenchyma
C. Distribution of axial parenchyma
D. Distribution of vessels
E. Structure of rays
F. Characters used in identification of wood

4. W O O D A N AT O M Y:
C O N I F E R O U S A N D
A N G I O S P E R M W O O D

5. C O N I F E R O U S W O O D

6. Also known as softwood
Homogenous & simpler in structure
Suitable for paper making
Source of commercial timber
Bamboo is a type of coniferous wood which is used in many ways in Asia
Absence of vessels
Small amount of parenchyma, particularly axial parenchyma
Resin ducts are present in most of the conifer wood

7. Pinus
Picea
Cathaya Larix
Pseudotsuga

8. A N G I O S P E R M W O O D

9. Complex wood structure
One of the most complex wood is that of oak
Contains vessel elements, tracheid, fibre-tracheids, libriform fibers, axial
parenchyma and rays.
Vessel less angiosperm woods can be distinguished from the conifer woods by
their tall broad rays.
Complexity = easy identification
Porous = presence of vessel
1. Diffuse porous and
2. Ring porous

10. Diffuse porous woods are uniform in size and distribution in the growth ring
In ring-porous woods the earlywood are distinctly larger than that of latewood
There is abrupt transition between early and latewood of the same growth ring
It may change due to environmental conditions, physical disturbance and as
well as change in the age.
Populus euphratica showed vigorous shoot growth in ample
water supply with wide annual rings and diffuse-porous wood but the trees
found on the dry site had narrow annual rings and ring-porous wood
Carlquist recognized 15 different kinds of growth rings
According to the hypothesis given by Aloni ring-porous wood has evolved from
diffuse-porous wood under selective environment.

11. Growth ring Carlquist
Populus euphratica

12. PA R E N C H Y M A : S T O R I E D
A N D N O N - S T O R I E D W O O D
PA R E N C H Y M A

13. The horizontal layers which are displayed clearly are known as storied or
stratified wood
The cell of one tier unevenly overlap those of another is known as non-storied
or Non stratified wood
Tangential sections are taken to see the storied wood structure
Storied woods are more highly specialized than nonstoried wood
Derived from vascular cambia and have short vessel elements
Intermediate patterns are found between the strictly storied woods and strictly
nonstoried woods
Storied woods are found only in eudicots but remains unknown in conifers.

14. E X A M P L E S O F S T O R I E D W O O D
Aesculus
Swietenia
Tilia
Diospyros

15. E X A M P L E O F
N O N - S T O R I E D
W O O D
Oak
Walnut
Mango Acer

16. D I S T R I B U T I O N O F A X I A L
PA R E N C H Y M A

17. Axial parenchyma consists of axially elongate cells or strands of cells, alive at
maturity, derived from fusiform cambial initials.
Axial parenchyma cells are usually thinner-walled than the imperforate
tracheary elements with which they are associated.
Each cell in a strand of axial parenchyma is usually surrounded by a secondary
wall.
Axial parenchyma distributions are invariably illustrated in transection
One can most easily distinguish axial parenchyma from other cell types (most
notably imperforate tracheary elements) in radial sections.
Once one has recognized axial parenchyma cells in a radial section, one can
apply the appearances discerned to what one sees in transections and
tangential sections.

20. D I S T R I B U T I O N O F
V E S S E L S

21. Within the main distribution patterns of vessels, minor variations occur in the
spatial relation of pores to each other.
Solitary pore: single pore with surrounding cells
Pore multiple: when 2 or more pores are present
1. Radial pore multiple &
2. Pore cluster
Appearance isolated but in real they are inter-connected
According to Zimmermann vessel groups are better than solitary vessel
because they provide alternative path for the xylem sap to bypass embolisms.

23. S T R U C T U R E O F R AY S

24. The ray parenchyma cells vary in shape but two fundamental forms may be
distinguished:
1. Procumbent ray cell: longest axes oriented radially
2. Upright ray cells: longest axes oriented vertically
Ray cells appear square in radial sections of wood are called square ray cells-
modification of upright ray cells
Ray cells that are composed only of of either one type is known as homocellular
and the ray cells with both the type is known as heterocellular
Angiosperm may have uniseriate as well as multiseriate rays which may range
in height from 1 cell to many cell
Several individual rays may be so closely associated with one another that they
appear to be one large ray known as aggregate rays.

26. C H A R A C T E R S U S E D I N
I D E N T I F I C AT I O N O F W O O D

27. 1. Color in wood is variable both between different
kinds of wood and within a species. Color of
heartwood.
2. Grain in wood refers to the direction of alignment
of the axial components — fibers, tracheid,
vessel elements, and parenchyma cells — when
considered all together.
3. Texture of wood refers to the relative size and
degree of size variation of elements within the
growth rings.
4. Figure refers to the pattern found on the
longitudinal surfaces of wood. In restricted sense
the term "figure" is used to more decorative
woods. Ex. Bird's eye maple, etc.

28. R E F E R E N C E S & S O U R C E S

29. • Esau's Plant Anatomy by Ray F. Evert
• https://www.brainkart.com/article/Secondary-Growth-in-Dicot-Stem_33049/
• https://link.springer.com/chapter/10.1007/978-3-662-21714-6_5?noAccess=true
• https://www.researchgate.net/publication/259878172_Symplasmic_networks_in
_secondary_vascular_tissues_Parenchyma_distribution_and_activity_supportin
g_long-distance_transport/figures?lo=1

30. T H A N K Y O U