1. Plant Tissues Michael Pettibon

2. Concept of Tissue

3. Primary Tissues Systems Meristems Dermal Ground Vascular

4. Origin of Primary Tissues Apical Meristems Protoderm Dermis (epidermis and periderm) Ground Meristems Ground Tissues (parachyma, collenchyma, and sclerenchyma) Procambium Primary xylem and phloem (vascular tissue system)

5. The General Location of the Primary Tissue Systems in a Dicot Root

6. Apical Meristems Responsible for the primary body of the plant and for the increase in length of the plant. –Protoderm gives rise to the dermal tissue –Procambium gives rise to the vascular tissue –Ground meristem gives rise to the ground tissue Pith – found in the center of the stems and some roots Cortex – formed under the epidermis

7. Lateral Meristems Responsible for increase in plant diameter or girth, known as secondary growth. Form in mature regions of the roots and shoots. Serves to make the plant sturdier. Two types 1.Vascular cambium – produces secondary xylem and phloem (vascular tissues). Runs the length of the stems and roots. 2.Cork cambium – produces periderm which helps protects the underlying tissues.

8. Ground Tissues Tissues that occur throughout the plant and function for storage, metabolism and support. Three type of cells; –Parenchyma; thin walled cells with primary cell walls only, found throughout the plant, form the pith and cortex tissues. Responsible for wound healing. –Collenchyma; thick cell walls, form under the epidermis of the plant and near the petioles. Used for support in young plants. –Sclerenchyma: tough, thick cell walls occurs in all of the primary and secondary plant bodies. Cell walls impregnated with lignin (polysacc.). Two types occur Sclerids – varied branched, gritty taste in pears is due to sclerids Fibers – long, slender cells that occur in bundles.

9. Dermal Tissues Epidermis – outermost layer of the leaves, fruit, and roots. Cuticle helps prevent water loss and stomata cells aerate internal tissues and regulate amount of gases and water vapor in the aerial parts of the plants. –Guard cells regulate the opening of the stomata Periderm – Located under the epidermis, replace epidermis as the protective tissues in the roots and stems.

10. A Close View of the Guard cells, Subsidiary Cells, and Other Epidermal Cells

11. The General Location of the Primary Tissue Systems in a Dicot Stem

12. PRIMARY VASCULAR TISSUES Complex tissues –Xylem –Phloem Origin: –procambium

13. Vascular Tissues Xylem – water and mineral conducting tissue in plants, mechanical support and storage of water and nutrients. Two types of cells; –Tracheid – mainly found in gynosperms and seedless vascular plants. –Vessel Elements – chief water conducting element in angiosperms. –Parenchyma – storage –Fibers – storage and support

14. XYLEM Origin: –primary procambium –secondary vascular cambium

15. XYLEM Tracheids –long cells with pits and lignified wall –slanted end walls to place as many pits as possible. –most primitive type of cells –Found primarily in gymnosperms (non- flowering plants such as pines and spruces)

16. XYLEM Vessels –Vessel members –single units of vessel members form a vessel –end walls are perforated The primary wall is dissolved leaving a large hole between two elements: perforation plate –Found primarily in angiosperms (flowering plants.

17. Phloem Conduct dissolved food (mainly sucrose) –Four types of phloem cells Sieve cells Albuminous cells Sieve tube elements Companion cells Parenchyma – storage Fibers – storage and support

18. Phloem Origin: –primary procambium –secondary vascular cambium

19. Phloem Sieve cells –Elongated in shape and tapered –Main food conducting cell in gymnosperms Albuminous cells –Exist closely with the sieve cells –Aid in the movement of food, informational molecules and ATP into and out of the sieve cells.

20. Phloem Sieve tube elements –Long, food conducting cells in angiosperms. –Only cell in plants that lack nuclei, but are living. –Have sieve areas and a plate with larger sieves at either end called sieve plates. Companion cells –Exist in association with the sieve tube elements and aid in the movement of food, informational molecules and ATP into and out of the sieve cells