BOTA 205 Lecture 6 Plant Cell and Tissue Systems

Plant Tissue

A group of cells that forms a structural and functional unit in plants; cells work together to perform specific tasks.

Three Plant Tissue Systems

Ground tissue, vascular tissue, and dermal tissue.

Ground Tissue System

Responsible for metabolism, storage, and support; includes parenchyma, collenchyma, and sclerenchyma.

Vascular Tissue System

Transports water, sugars, and minerals; includes xylem and phloem.

Dermal Tissue System

Forms the plant’s outer protective layer (“skin”); includes epidermis and periderm.

Simple Tissue

A tissue made up of only one primary cell type; includes parenchyma, collenchyma, and sclerenchyma.

Complex Tissue

A tissue made of multiple cell types working together; includes vascular and dermal tissues.

Cell Wall Importance

The structure of the cell wall distinguishes one ground tissue from another and determines function.

Parenchyma

Least specialized plant cell type; performs metabolic functions and can divide to form new cells.

Parenchyma Cell Wall

Thin, flexible primary walls allow metabolic activity and flexibility.

Parenchyma Functions

Photosynthesis, storage, secretion, and repair due to totipotency.

Totipotency

The ability of a cell to divide and form new, undifferentiated cells for repair or new growth.

Collenchyma Tissue Function

Provides flexible support for young, growing parts of plants like shoots and petioles.

Collenchyma Cell Wall

Unevenly thickened primary walls, often thickest at corners; allows flexibility with strength.

Collenchyma Cell Arrangement

Usually grouped in strands or cylinders for structural support.

Collenchyma at maturity

Living at maturity but metabolically inactive; provides mechanical support only.

Sclerenchyma Tissue

Provides rigid, permanent strength for mature plant parts.

Sclerenchyma Cell Wall

Thick secondary walls with lignin for hardness and rigidity.

Sclerenchyma at Maturity

Non-living at maturity; serves only structural roles.

Lignin

A complex polymer in secondary cell walls that adds rigidity and waterproofing.

Sclerenchyma Cell Types

Fibers (long, slender) and sclereids (short, irregular); sclereids give pears their gritty texture.

Sclerenchyma fucntions

Provides a plant with rigid support in the mature parts

Fibers

Long, thread-like sclerenchyma cells that form supportive bundles.

Sclereids

Short, irregular sclerenchyma cells found in nutshells and gritty fruits.