Botany lecture notes

Difference between Heartwood and Sapwood


Difference Duramen and Alburnum

Heartwood vs Sapwood
(Similarities and Differences between Heartwood and Sapwood)

Anatomically, wood is the secondary xylem of seed-plants. As the tree ages, certain permanent changes take place in the wood. The inner parts of the wood become darker. The xylem in this central part is called heartwood or ‘duramen’. The peripheral part of the wood is light coloured and it is called sapwood or ‘alburnum’. The sap conduction occurs through the sapwood. The dark colour of heartwood is due to the accumulation many aromatic substances, pigments and tannins. These changes make the wood more strong and durable and resistant to decay by insect or fungal attacks. The inner heartwood provides the mechanical support. The present post discusses the similarities and differences between heartwood and soft wood with a comparison table.

Similarities between Heartwood and Sapwood

Ø  Both are composed of secondary xylem formed after many years of secondary growth.

Ø  Both are derived from the vascular cambium.

Ø  Both can provide mechanical support.

Continue reading

Botany lecture notes

Difference between Hardwood and Softwood


Difference between Porous and Nonporous Wood

Hardwood vs Softwood
(Similarities and Differences between Soft Wood and Hard Wood)

Anatomically ‘wood’ is the secondary xylem of plants. Commercially there are two categories of wood based on its source. They are (1) Hardwood and (2) Softwood.

(1). Hardwood: The wood of dicot Angiosperms is called hardwood. Hardwood and heavy since it contains plenty of wood fibres (fibre tracheids and libriform fibres).

(2). Softwood: The wood of Gymnosperms is called softwood. The softwood mainly composed of tracheids and wood rays (parenchyma).

List of Hardwood trees: Teak, Rosewood, Mahogany, Oak, Sal-tree, Alnus, American chestnut etc.

List of Softwood trees: Araucaria (monkey puzzle tree), Cedar, Cypress, Fir (Abies), Pine (Pinus), Larch (Larix) etc.

The present post discuss the similarities and differences between Hardwood and Softwood with a Comparison Table

Similarities between Hardwood and Softwood

Ø  Both hardwood and softwood are secondary xylem.

Ø  Both contain tracheids and parenchyma.

Ø  Both are heavy and hard.

Ø  Both kinds of woods are economically valuable as timbers.

Difference between Softwood and hardwood

Difference between Hardwood and Softwood

Continue reading

Botany lecture notes

Difference between Collateral and Bicollateral Vascular Bundles


Collateral vs Bicollateral vascular bundle

Collateral vs Bicollateral Vascular Bundles
(Similarities and Differences between Collateral and Bicollateral Vascular Bundles)

Vascular bundles are the distinct structural organization vascular tissues (xylem and phloem) and the formation of vascular bundles is one of the advanced characteristics of higher plants. In the stem of seed plants, the vascular tissue (xylem and phloem) occupy together as vascular bundles. However, in roots the xylem and phloem are not associated together and not form the vascular bundles. Such an arrangement of vascular tissue in root is called radial arrangement. In the previous post we have discussed the Structure and Classification of Vascular Bundles. Based on the relative position and number of phloem strands in vascular bundles, the conjoint vascular bundles are classified into two groups: (1). Collateral vascular bundles and (2) Bicollateral vascular bundles.

Bi-collateral vascular bundles(1). Collateral vascular bundle: A type of conjoint vascular bundle where the xylem occupies inner to a single strand of phloem. Example: dicot stem and monocot stem.

(2). Bicollateral vascular bundles: A type of conjoint vascular bundle where the xylem is situated in the middle of two phloem strands. Example: stem of Cucurbita, Cephalandra (members of Cucurbitaceae Family).

The present post describes the similarities and differences between the collateral and bicollateral vascular bundles in plants with a comparison table.

Similarities between Collateral and Bicollateral Vascular Bundles

Ø  Both are conjoint vascular bundles (xylem and phloem occupy together as bundle).

Ø  Both are present in the stem.

Ø  Both contain only one xylem strand.

Ø  Xylem is endarch in both the groups.

Difference between Collateral and Bicollateral Vascular Bundle

Continue reading

Botany lecture notes

Difference between Fascicular and Interfascicular Cambium


Fasccular and Interfascicular Cambia

Fascicular vs Inter-fascicular Cambium
(Similarities and Differences between Fascicular and Interfascicular Cambium)

Cambium is a strip of meristematic cells present between the xylem and phloem in dicot plants. The primary function of the cambium is to produce the vascular tissue and hence it is called the ‘Vascular Cambium’. The vascular bundles found in the primary plant parts are also called as Fascicles. The vascular cambium produces xylem towards the inner side and phloem towards the outer side in both stem and roots. There are two types of vascular cambium in dicot plants based on its position; they are (1) Fascicular Cambium and (2) Interfascicular Cambium.

(1). Fascicular cambium: The cambium present between the xylem and phloem of a vascular bundle is called fascicular cambium. The fascicular cambium is also called as intrafascicular cambium since they are present inside the vascular bundle. In the beginning, the fascicular cambium is a primary meristem, later during the secondary growth; it gets transformed into a secondary meristem.

(2). Interfascicular cambium: The cambium occupy between two vascular bundles is called interfascicular cambium. It is a secondary meristem.

During the secondary growth in a dicot stem, the fascicular and interfascicular cambium fuse together to form a continuous ring of meristematic tissue called the Vascular Cambium. The vascular cambium cut-off the secondary xylem towards its inner side and secondary phloem towards its outer side.

The present post describes the similarities and differences between Fascicular and Interfascicular Cambium.

Similarities between Fascicular and Inter-fascicular cambium

Ø  Both fascicular and interfascicular cambia are meristematic cells.

Ø  Both are the part of vascular cambium.

Ø  Both can produce xylem towards the inner side and phloem towards the outer side.

Ø  Both are actively dividing cells.

Difference between Fascicular and Interfascicular Cambium

Continue reading

Botany lecture notes

Difference between Phellem and Phelloderm

Phellem vs Phelloderm

Phellem vs Phelloderm
(Similarities and Differences between Phellem and Phelloderm)

During the secondary growth in both stem and root, the peripheral tissues like epidermis, hypodermis and cortex are replaced by a new secondary tissue called the Periderm (bark). The periderm composed of three components: (1) Phellogen, (2) Phellem and (3) Phelloderm.

(1). Phellogen: Phellogen is the cork cambium, a layer of meristematic tissue which produces the phellem and Phellogen together known as the periderm or bark.

(2). Phellem: Phellem is the actual cork, produce by the phellogen towards the outer side.

(3). Phelloderm: Phelloderm is the secondary cortex, produced by the phellogen towards the inner side.

Even though the phellem (cork) and phelloderm (secondary cortex) are produced by the same meristematic tissue (phellogen), they show many differences. The current post discusses the Similarities and Differences between the Phellem and Phelloderm with a Comparison Table.

Similarities between Phellem and Phelloderm

Ø  Both phellem and phelloderm are secondary tissues.

Ø  Both are produced by the cork cambium – phellogen.

Ø  Both are parenchymatous cells.

Ø  Both form the component of bark.

Difference between Phellem and Phelloderm

Continue reading