Medicinal Plants Lecture 6

Vascular bundles are structures in plants that contain phloem and xylem tissues, responsible for transport of water, nutrients, and sugars.

Dicot stems have vascular bundles arranged in a ring with cambium in between xylem and phloem, while monocots have scattered vascular bundles without cambium.

Dicot leaf vascular bundles typically have a network of veins.

Monocot leaf vascular bundles usually have parallel veins.

Cambium is a layer of meristematic cells that produces new xylem and phloem cells, allowing for secondary growth in dicots.

Growth rings in trees, formed by differing thicknesses of wood during seasons.

Wider wood cells formed in the spring when new growth occurs.

The wider wood formed in the spring due to new growth.

Structures in trees which transport water.

Parts of a plant that grow during the spring.

The denser wood formed during the later part of the growing season (summer or early autumn), typically characterized by smaller, thicker-walled cells.

The visible concentric circles on the cross-section of a tree trunk, representing one year of growth.

While there's no distinct line within a single ring, the late wood of one year and the early wood of the next year are separated by a sharp line.

Within a single annual ring, the late wood is denser due to smaller, thicker-walled cells compared to the early wood.

The outer layer of wood in a tree that transports water and nutrients. This active layer is composed of living cells.

The inner, non-functional core of a tree. It is composed of dead cells and provides structural support.

In most trees, the cells responsible for water transport within the vascular system live for only a short time, often just one year.

As sapwood ages, the cells die and become filled with resins and other compounds, turning into heartwood. This process strengthens the wood.

Heartwood is darker because it contains resins and other compounds that accumulate over time as the cells die.

Protrusions of pit membranes from living parenchyma cells that block the lumen of vessels or tracheids.

The thin wall separating two adjacent cells, allowing communication through pits.

A type of pit with a thickened border on one side.

Living cells in plant tissue that perform various functions, including storage and photosynthesis.

The hollow interior space of vessels or tracheids.

Xylem and phloem are conducting tissues responsible for transporting water, nutrients, and sugars throughout the plant.

Chloroplasts are responsible for photosynthesis, the process by which plants convert light energy into chemical energy.

Endarch xylem is the arrangement of xylem in roots where the protoxylem (older xylem) is located towards the center of the root, while the metaxylem (younger xylem) is located towards the outer part.

Lenticels are structures that replace the function of stomata in woody stems, allowing for gas exchange.

Annual rings are formed due to the different thicknesses of wood produced during spring and summer, creating visible rings in the stem.