one tier appear at approximately same level and several clear-cut tiers (strata) are seen. In a non- storied wood the wood elements are not arranged in clear-cut tiers. The cells of one tier overlap the other. Storied wood is seen in Quercus, while non-storied wood is seen in Ficus. From the phylogenetical standpoint; storied wood is regarded as more advanced than non-storied wood.
• Grains: The size, shape and arrangement of cells in the wood contributing to the variation in appearance is referred to as the grains of wood. Grains may be coarse, fine or arranged cross wise.
In a spiral grain, the cell systems wind spirally around the tree. Wood structure, annual rings and wood ray together constitute the conspicuous grain of wood. In trees like Quercus, where the wood rays are large and dense, they take a high polish and are referred to as the silver grains. In certain trees, numerous adventitious buds remain dormant under the bark and represent areas of parenchyma. In a cross section, the fibres and other xylem elements swing around the buds or
‘eyes’. Such grains are called bird’s eye grains.
• Compression wood: In many conifers, the under side of the branches has a type of wood called compression wood. It is darker than the sap wood and reddish in color resembling the heartwood.
It is also called red wood because of its color. It is more brittle than the normal wood.
the wood mainly depends on its composition. The presence of large amount of fibres or fibre trachiedes makes a wood very strong.
3. Durability: The capacity of the wood to resist the attack of fungi and bacteria and thus remain strong for a very long time is called the durability. This is dependent on the chemical composition of the wood. Generally heart wood is durable because it has no food or living contents to offer to the invading organisms, besides the tannins and oils act as antibacterial and antifungal agents. The durability of the wood is not dependent on its weight.
4. Wood Seasoning: The process of drying the wood (so that it loses its water content) before it is used for any purpose is called seasoning. If the wood is used before seasoning it tends to crack, shrink or break as it loses water. In a seasoned wood, ther is no moisture and the wood retains its shape without shrinking. Exposing the wood to the heat of the sun by keeping them in shades may do seasoning. This method is called air seasoning. In kiln seasoning heat is applied to wood in an enclosed space by circulating hot air. Kiln seasoning takes a much shorter period than air seasoning.
Some Important Timber Yielding Plant and their Uses:
Wood is a versatile material and finds extensive use in various human endeavors. The following are some of the uses of timber (wood).
• Structural timbers: These are used for buildings. Strength and durability of the wood is important. Wood is used for doors, windows, frames, beams etc. Suitable trees are-Tectona grandis, Toona ciliata, Hopea parviflora, Bischofia javanica, Shorea robusta, Mangifera indica, Tamarindus indica, Terminalia arjuna, Lagerostromia lanceolata, Pterocarpus indica
• Construction of Bridges: A strong and highly durable wood is needed for bridge construction.
Tree used for this purpose are: Hopea parviflora, Mesua spp, Anogeissus latifollia,Tectona grandis
• Timber used for Transport and Communication: Many trees yield valuable wood used for railway sleepers, piles of bridges and telegraph, telephone and transmission poles. Strength, toughness, resistance to decay is important for railway sleepers. Piles used for bridges should have strength, durability, and resistance to shearing, crushing and splitting.
• Timber used for Ship, Boat building etc: Many trees are highly suitable as they remain strong even after a long contact with water. These woods will not decay easily. Trees used for marine work should resist marine borers. These are-Tectona grandis, Xylia xylocarpa, Stereospermum suaveolens
• In fresh water, piles used in contact with water will remain strong if they are completely submerged in water. But when they are alternately exposed and submerged, the wood is generally treated with certain chemicals to prevent decay. Trees suitable for fresh water piles are- Acacia nilotica, Bischofia javanica, Xylia xylocarpa etc.
In ship and boat building various trees are used for a variety of purposes. These are:
a) For hulls: Calophyllum inophyllum
Hopea parviflora
Lagerostromia microcarpa etc.
b) For ribs: Thespesia populenea
c) Deck planking: Adina cordifolia
Gmelina arborea
Mangifera indica
d) Oars: Grewia tilifolia
The wood used for ship and boat building has to be treated with fish oil, tar etc to prevent attack by marine organisms (Fungi, etc.)
1. Timber used in Cabinet making: Many of the timber trees specially preferred for joinery, furniture etc, as they are not only strong and durable but take a fine polish giving a beautiful appearance, there should be good grains in the wood to give a good look. Some of these trees are-
a. Joinery: Dysoxylum malabaricum Hopea parviflora
Lagerostromia lanceolata
Terminalia paniculata
b. Cabinets: Tectona grandis
Dalbergia latifolia
Dispyros ebenum
Chloroxylon switenia
Santalum album. sandalwood is used for caskets and carving as it is fragrant and pliable.
c. Furnitures: Dalbergia latifolia Tectona grandis
Dysoxylum malabaricum Kirugiodendron pinnatum
d. Ornamental veneers: These give a fine-grained appearance after polishing. Trees used for this purpose are-
Tectona grandis
Dalbergia sissoo
Toona ciliata
Switentia mahagony etc
e. Plywood: Used for shelves, partitions etc Vateria indica
Dipterocarpus indicus
Canarium strictum
Bombax malabaricum
2. Timber used in transportation vehicles. Frames of railway carriages, carts and other types of vehicles (body building) need good timber. Wood for frame should be light and strong.
a. Wood for frames: Shorea roxburghii
Gmelina arborea
b. Axles and hubs: Acacia nilotica
Anogeissus latifolia
Dalbergia sissoo
Xylia xylocarpa
` Hopea parviflora
c. Spokes (for carts): Acacia nilotica
Anogeissus latifolila Xylia xylocarpa
Dalbergia spp
Lagerostromia spp
d. Shafts: Shorea sp.
Grewia tilifolia
Pterospermum suberifolium
e. Rims: Vitex leucoxylon
Xylia xylocarpa Mangifera indica
3. Wood used for tool handles: The wood suitable for tool handles must have closely located grains, must be tough and not liable to split.
The texture of the wood should be smooth and as to be easily handled. The wood used for this purpose belongs to:
Acacia nilotica
Grewia tiliifolia Anogeissus latifolia Schleichera oleosa
Mesua nagassarium
4. Wood used for packaging boxes: Wood used for this purpose must be light as it can be easily transported. But it should be sufficiently strong to withstand damages. Trees that yield wood for this purpose are-
Alstonia scholaris Vateria indica
Holoptelea integrifolia Bombax malabaricum
5. Wood used for match boxes: Wood should be light and soft.
Bombax malabaricum
Ailanthus malabaricum Alstonia scholaris Symplocus spicata
6. Wood used for sports goods: Cricket bats, Hockey sticks, tennis rackets are made out Morus alba, Salix tetrasperma, Thespesia populnea.
7. Musical instruments : Many musical instruments like flute are made out of wood of Bambusa spp, others like Tectona grandis, Switentia mahagony are also used
8. Fire wood: Fire wood is provided by practically all trees which have a sufficient amount of secondary wood ex. Tamarindus indica, Mangifera indica, Acacia spp., Anogeissus latifolia, Prosopis juliflora are common source of fire wood.