BIO 3015 - Types of Tissues

Tissue Systems

Ground tissue system, vascular tissue system, and dermal tissue system.

Simple Tissues

Tissues that are composed of one cell type. Perform essential functions, such as photosynthesis, support, storage, regulation

Types of Simple Tissue

Parenchyma, collenchyma, sclerenchyma

Parenchyma Cells

Usually spherical or elongated, but can have

different shapes. Thin primary cell walls, but may develop

lignified secondary walls. They help with photosynthesis respiration storage and secretion

Parenchyma Tissue

Composed of parenchyma cells. In the cortex and pith they can serve a storage and support purposes. In the mesophyll: can serve a photosynthetic (palisade) and regulatory (spongy) role.

Collenchyma Cells & Tissue

Elongated, often containing chloroplast, and alive at maturity. Cell walls composed of alternating layers of pectin and cellulose - usually thicken at the corners. Outermost cells of cortex - might aggregate into rights around the stem.

Sclerenchyma Cells & Tissue

Thick, lignified secondary cell walls. Dead at maturity

Come in two types of cells fibers and sclerids

Fibers

Long, narrow cells with thick, pitted cell walls tappered at the ends. Can aggregate into continuous cylinder around stems or form strands.

Sclerids

These cells can have many shapes (from simple stone shapes to highly branched). These cells can form sheets (e.g. seed coat) or be in small clusters

Complex Tissue

Interconnected network of cells transversing the

entire plant. Composed of: Vessel elements and tracheids (water-conducting cells), Fibers (sclerenchyma cells for support), Living parenchyma cells (help load minerals in

and out of conducting cells), Sieve-tube members (food conducting cells) and Companion cells (specialized parenchyma cell).

Complex Tissue: Epidermis

Usually a single layer of cells in the outer part of the

plant - as many as 6 layers in succulent plants. Covered in cutin. Composed of Epidermal cells, Guard cells, and Subsidiary cells

Trichomes

Outgrowths of one or more cells - in roots, they form root hairs. In leaves and stems, they can form protective structures

Complex Tissue: Periderm

A protective layer that forms in older stems and

roots - replaces the epidermis. A secondary tissue composed of: Phellem (cork) cells on the outside. Dead at maturity and with waxy suberin embedded in the cell walls

Phelloderm

Parenchyma-like cells between the cork cambium and cortex.