Plant Structure and Function Ch. 35

1. Plant Structure and FunctionCh. 35 http://www.uic.edu/classes/bios/bios100/labs/plantbod.gif

2. Morphology of a Flowering Plant • Root system and shoot system are connected by vascular tissue that is continuous throughout plant

3. Monocots vs. Dicots

4. http://www.biologie.uni-hamburg.de/b-online/library/onlinebio/monocot_flower.gifhttp://www.biologie.uni-hamburg.de/b-online/library/onlinebio/monocot_flower.gif http://waynesword.palomar.edu/images/monocot3.gif http://www.biology4kids.com/misc/photos/dicotflower1.jpg http://waynesword.palomar.edu/images/monocot3.gif

5. Nucleus Chloroplast Cell Wall Plant Cell

6. Roots • Functions • Anchor plant in the soil • Absorb water and minerals • Store food

7. Root Structure

8. Root Systems Taproot Fibrous root

9. http://waynesword.palomar.edu/images/mangro3b.jpg http://waynesword.palomar.edu/images/mangro3b.jpg • Red mangrove growing in seawater • Adventitious prop roots support and securely anchor this shrub in the mud and loose sand of tidal waters. • Close-up view of prop roots • Numerous pores called lenticels which provide gas exchange and an additional source of oxygen for the submersed roots.

11. Epidermis Cortex Vascular cylinder -xylem -phloem Developing lateral root

13. Modified Roots Storage roots. Prop root Buttress roots. Aerial roots

14. Stems • Functions • Support • Transport • Storage

15. Monocot arrangement

16. Dicot arrangement

17. Proximity of terminal bud inhibits growth of axillary buds (Apical dominance) http://www.answers.com/topic/redtip9845-jpg-1

18. Modified Stems Stolons—allow asexual reproduction Bulbs—store food Tubers—store food Rhizomes—horizontal stem

19. Leaves • Leaf structure • Shape • Size • Edges

20. Leaf Structure Mesophyll

22. Stomata

23. Modified Leaves • Tendrils—allow plant to cling to support • Spines—reduces water loss

24. Modified Leaves • Storage—modified for water storage (succulents) • Bracts—attracts pollinators

25. Modified Leaves • Reproductive leaves—produce adventitious plantlets which fall off and take root

26. Tissue Systems 1. Ground System • Parenchyma • Collenchyma • Sclerenchyma --cube-shaped, thin and flexible cell walls --function in photosynthesizing and storing organic products and wound healing --elongated, thicker cell walls --cells grouped in strands or cylinders to support leaves and stems (parts that are still growing) --cells have rigid, thick walls with lignin --at maturity, consists of dead cells --supports and strengthens plant

29. Tissue Systems -Conducts water and minerals from roots to plant -composed of dead cells that form water-pipe system Xylem -Conducts food throughout plant -composed of living cells arranged into tubules Phloem 2. Vascular System

30. Water-conducting Cells of Xylem

31. Sugar-conducting Cells of Phloem

32. Sheath of sclerenchyma phloem xylem parenchyma

33. Tissue Systems 3. Dermal Tissue System - Forms the outer covering of plants • Epidermis-outer layer of cells • covered by waxy cuticle • Stomata-structures that regulate • passage of gases into/out of plant

34. Meristems: Primary Growth Growing region where cells actively divide Apical meristems- grow in length at tips of stems and roots

35. Lateral meristems • Add thickness to woody plants, a process called secondary growth • Two lateral meristems • vascular cambium adds layers of vascular tissue called secondary xylem (wood) and secondary phloem • cork cambium replaces the epidermis with periderm, which is thicker and tougher

36. Primary Growth in Roots

37. Primary Growth in Shoots

38. Secondary growth occurs in stems and roots of woody plants but rarely in leaves • Vascular cambium • Produces secondary xylem and phloem • Cork cambium • Produces tough, thick covering for stems and roots • Replaces epidermis

39. Anatomy of a Tree Trunk • As a tree or woody shrub ages, the older layers of secondary xylem, the heartwood, no longer transport water and minerals • The outer layers, known as sapwood, still transport materials through the xylem

40. Growth, morphogenesis, and differentiation produce the plant body • The three developmental processes of growth, morphogenesis, and cellular differentiation act in concert to transform the fertilized egg into a plant

41. Growth: Cell Division and Cell Expansion • By increasing cell number, cell division in meristems increases the potential for growth • Cell expansion accounts for the actual increase in plant size

42. The Plane and Symmetry of Cell Division • The plane (direction) and symmetry of cell division are immensely important in determining plant form • If the planes of division are parallel to the plane of the first division, a single file of cells is produced

43. The Plane and Symmetry of Cell Division • If the planes of division vary randomly, asymmetrical cell division occurs

44. The Plane and Symmetry of Cell Division • The plane in which a cell divides is determined during late interphase • Microtubules become concentrated into a ring called the preprophase band

45. Genetic Control of Flowering • Flower formation involves a phase change from vegetative growth to reproductive growth • It is triggered by a combination of environmental cues and internal signals • Transition from vegetative growth to flowering is associated with the switching-on of floral meristem identity genes

46. Plant biologists have identified several organ identity genes that regulate the development of floral pattern

47. The ABC model of flower formation identifies how floral organ identity genes direct the formation of the four types of floral organs