Plant Cells and Tissues

I. General Information A. Three main plant cell types 1. Parenchyma 2. Collenchyma 3. Sclerenchyma

1. Parenchyma Can differentiate into all cell types Living cell, can still divide F(x)s = Plant growth Food production (photosynthesis) Food storage (e.g. potatoes) Wound healing & regeneration

2. Collenchyma a. Living cells b. Have thicker walls than parenchyma c. Can form long rope-like fibers (e.g. linen) d. Can stretch (occur in elongation zones) e. F(x) = strength, support, elongation

3. Sclerenchyma Usually dead while functioning Thick secondary wall, no stretch F(x) = strength, support 2 types: i. fibers ii. Sclereids (seed coats, nut shells & fruit)

I. General Information B. Three main types of plant tissue 1. Ground tissue 2. Dermal Tissue 3. Vascular Tissue

C. Ground tissue 1. Surrounded by dermal tissue 2. All tissue that is NOT dermal tissue or vascular tissue

C. Ground tissue 3. Contains all three types of cells (mostly parenchyma) 4. Make up most of non-woody roots, stems & leaves

C. Ground tissue 5. Many f(x)s Photosynthesis Food storage Support

C. Ground tissue

D. Dermal Tissue 1. General Forms the “skin” (outside covering) of a plant b. Covers roots, stems & leaves c. F(x) depends on location

D. Dermal Tissue Epidermis Cuticle Root Hairs Stomata Cork d. Examples: Epidermis Cuticle Root Hairs Stomata Cork

D. Dermal Tissue 2. Epidermis a. Parenchyma b. Usually ONE cell thick c. Outer protective covering of young & mature woody plants

D. Dermal Tissue Waxy layer secreted by epidermis prevent dehydration 3. Cuticle Waxy layer secreted by epidermis b. F(x) = prevent dehydration

D. Dermal Tissue 4. Root Hairs Modification of epidermis b. F(x) =Absorption of water from soil

D. Dermal Tissue a. Location = stems & leaves 5. Stomata a. Location = stems & leaves b. F(x) = osmoregulation & regulation of gas exchange

D. Dermal Tissue c. Composition: two guard cells stoma (opening)

D. Dermal Tissue cork 6. Cork (bark) (Dead cells) F(x) = i. Replace epidermis in woody stems & roots ii. Protect plant

E. Vascular Tissue F(x)s a. Transports water & nutrients b. Supports the plant

E. Vascular Tissue 2. Two kinds of vascular tissue a. Xylem b. Phloem

E. Vascular Tissue F(x) = Conducts Water & Nutrients UP from roots 3. Xylem F(x) = Conducts Water & Nutrients UP from roots (X elevator only goes up)

3. Xylem b. Two kinds of conducting cells i. Tracheids long, thick-walled scelerenchyma Thin separations between them

i. Tracheids Water moves between them through PITS (thin porous areas of cell wall)

3. Xylem Short, wide sclerenchyma No end walls ii. Vessel Elements (members) Short, wide sclerenchyma No end walls No separations btwn. them (arranged end to end) Not found in Gymnosperms

Tracheids vs Vessel Elements

4. Phloem F(x) = conducts the Products of Photosynthesis in every direction (P elevator moves in every direction)

4. Phloem b. Two kinds of conducting cells 1. Sieve Tube Member a. F(x) = Conduct sap b. Stacked to form long SieveTubes

4. Phloem 2. Companion Cells a. Parenchyma b. F(x) = Control movement of sap through sieve tubes