PLANT TISSUESJhia Anjela D. Rivera1,2

1Department of Biology, College of Science, Polytechnic University of the Philippines2Department of Biological Sciences, School of Science and Technology, Centro Escolar University

Plant Tissues

Simple Permanent

Tissues

Epidermis

Parenchyma

Sclerenchyma

Collenchyma

Cork

Complex Permanent

Tissues

Xylem

Phloem

SIMPLE PERMANENT TISSUES

• Epidermis (outermost covering of plants)

• Parenchyma (food manufacturing and storage)

• Sclerenchyma (cells with tapering ends, provides strength)

• Collenchyma ( cube-like, provides strength)

• Cork (rectangular cells, for protection)

EPIDERMIS

• Outermost covering of plants

• Single layer of cells

• Rectangular and cube-like shaped

• Contains ordinary epidermal cells and guard cells

• Contains cutin (waxy substance that prevents water loss)

• Function:

• Mechanical support

• Protection from dessication, attack against virulent pathogenic organisms, gas exchange, restriction of water loss due to evaporation (transpiration)

EPIDERMIS

PARENCHYMA

• make up the major portion of the primary plant body

• thin-walled and vary in shape from spherical with many flat surfaces, to elongated, lobed, or folded

• found in photosynthetic tissue of green leaves and green stems, in epidermis

Function:

• Food manufacturing and storage

PARENCHYMA

SCLERENCHYMA

• Thick-walled tissue

• At maturity, some sclerenchyma cells no longer have living protoplasts

• contains large amounts of cellulose and lignin

• Has two types:• Fibers

• Sclereids

Function:

• Mechanical support

SCLERENCHYMA

• Sclereids:• dense (lignified), short cells which may look like stones, rods, bones, stars, or

branched structures

• occur in nut shells, fruit pits, and the seed coats

• Fibers:• elongated cells with pitted cell walls

• found in water-conducting tissue (xylem) and food-conducting tissue(phloem) along leaf veins and margins and surrounding vascular bundles in stems

COLLENCHYMA

• closely arranged, living cells are short or elongated in shape

• usually found near the surface in the cortex around vascular bundles of leaf petioles and stems

• Thick walled

Function:

• provide elastic support to stems and leaves due to variously thickened primary walls containing cellulose, hemicellulose, pectin, and water

CORK

• Dies immediately after being formed due to waxy substances present in its outer wall which does not allow substances to penetrate through its walls

• Appear as layered, rectangular cells

Function:• For protection

COMPLEX PERMANENT TISSUES

• Major types:• Vascular

• Conducting

Xylem (Water conducting tissue)

• Composed of several types of cells (living and non-living)• Tracheary elements: tracheids and vessel elements (water and nutrient

conduction)

• Fiber (provide support)

• Parenchyma cells (food storage)

Tracheary Elements

• Composed of tracheids and vessels

• Tracheids• are elongated, have bordered wall pit

• Aligned side by side

• Function: water conduction

• Vessels• Have bordered pits in their cell walls

• water- and mineral conducting cells of the xylem

Phloem: Food Conducting Tissue

• Composed of sieve elements:

• Sieve tubes (chief conducting cells of phloem)

• Companion cells (v), a specialized type of parenchyma

• Phloem fibers and Phloem parenchyma are also present

WAIT, THERE’S MORE!