1. 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. *See PowerPoint Lecture Outline for a complete, ready-made presentation integrating art and lecture notes. Introductory Plant Biology Ninth Edition Kingsley Stern Chapter 5 Image Slides*

2. Chapter 5 Roots

3. 3 Root function Anchor plant to soil absorb water and minerals in solution

4. 4 How roots develop Embryo- an immature plant Radicle- first root that grows out of an embryo

5. 5 2 types of mature roots 1. Taproot- large major root - pine trees, carrots 2. Fibrous roots- many branched roots; Adventitious roots- roots that develop from stem, leaf, etc.

6. 6 Fig. 5.1

7. 7 Root development in flowering plants 1. Dicotyledon- have 2 “seed leaves” - have taproots from which secondary roots develop - ex. Peas and carrots 2.Monocotyledon-have 1 “seed leaf” - have fibrous roots - ex. Corn and rice

8. 8 Root structure; 4 regions 1. Root cap- thimble-shaped mass of parenchyma cells - Protects the root from damage as it pushes through the dirt - Dictysomes produce slimy substance to help root move - Functions in the perception of gravity

9. 9 4 root regions cont. 2. Region of cell division- - composed of apical meristem in the center of the root tip - produces surrounding root cap

10. 10 3 types of meristem from apical meristem 1. Protoderm- forms epidermis 2. Ground meristem- forms cortex 3. Procambium- forms primary xylem and phloem

11. 11 4 root regions cont. 3. Regions of elongation- - 1cm from root tip - cells grow longer and wider - no further increase in cell size takes place above this region

12. 12 4 root regions cont. 4. Region of maturation/differentiation or “root hair zone”

13. 13 Fig. 5.2

14. 14 Cells and Tissues of Region of Maturation Root hairs - absorb water & minerals - hold tightly to soil - increase surface area - not separate cells; extensions of specialized epidermal cells - up to 250,000/in 2

15. 15 Fig. 5.4b

16. 16 Cells/Tissues cont. Cortex- parenchyma cells that lie between epidermis and inner tissues; stores food

17. 17 Cells/Tissues cont. Endodermis- separates cortex from vascular tissue - Consists of a single-layer cylinder of cells -Casparian strips- “mortar” of suberin around endodermis cells

18. 18 Cells/Tissues cont. Endodermis cont. Casparian strips- force all water and dissolved substances to pass through the plasma membrane or plasmodesmata of the endodermis - this regulates types of minerals absorbed

19. 19 Fig. 5.5

20. 20 Cells/Tissues cont. Vascular cylinder- inside area of endodermis - pericycle- parenchyma cells that give rise to lateral vascular cambium and lateral roots - primary xylem- central core; usually 4 arms - branch roots grow opposite of arms

21. 21 Cells/Tissues cont. Phloem- forms between xylem arms Vascular cambium- develops between xylem and phloem Cork cambium- woody plants only - arises outside vascular cambium - generally not found in monocots

22. 22 Fig. 5.6

23. 23 Tissue Development

24. 24 Specialized Roots Food storage roots- sweet potatoes, carrots Large number of parenchyma cells form in branch roots Store carbohydrates

25. 25 Specialized Roots Water-storage roots- - pumpkin family roots - plants store water in roots when water supply in soil is low

26. 26 Specialized Roots Propagative roots- - adventitious buds- buds appearing in places other than the stem - buds develop into aerial stems called suckers, with rootlets at base - found in cherry, apple, pear trees

27. 27 Specialized Roots Pneumatophores- special spongy roots which extend above the water’s surface to enhance O 2 supply - not cypress knees

28. 28 Specialized Roots Aerial roots- may support plant in high wind; aid in climbing Contractile roots- pull plant deeper into the soil Buttress roots- add stability

29. 29 Fig. 5.12

30. 30 Fig. 5.13

31. 31 Fig. 5.14

32. 32 Specialized Roots Parasitic roots- mistletoe - haustoria-(sing. haustorium) projections that develop along stem in contact with host - penetrate outer tissue and connect with host’s vascular tissue

33. 33 Mycorrhizae mycorrhizae- fungus roots - fungus grows on roots; can’t grow beyond Casparian strip - absorb phosphorus, water and minerals for the plant - fungus lives on plant’s sugar - ex. of mutualism

34. 34 Fig. 5.15

35. 35 Fig. 5.16ab

36. 36 Root Nodules root nodules- small swelling on roots filled with N 2 -fixing bacteria - found in Legumes

37. 37 Fig. 5.17

38. 38 Human Relevance of Roots food; carrots, sugar beets, turnips rutabagas, parsnips, horseradishes, sweet potatoes spices- sassafras, sarsaparilla, licorice dyes drugs insecticides

39. 39 Soil several types of sand, rocks, pebbles, clay, silt, small animals, bacteria, fungi Humus- decomposed organic matter

40. 40 Soil texture and mineral composition sand and silt- small particles clay- colloid-suspension of particles that are larger than molecules, but do not settle out of fluid loam-mixture of sand, clay organic matter - agricultural soil- 40% silt, 40% sand, 20% clay

41. 41 Table 5.1

42. 42 Minerals in soil include- O 2, H 2, Si, Al, Fe, K, Ca, Mg, Na

43. 43 Water in Soil Hygroscopic water- water bound to soil and not available to plants Gravitational water- drains out of pore spaces in soil after a rain Capillary water- held in pores in soil; water for plants Field capacity- water remaining after water in soil drains away

44. 44 Water in Soil Permanent wilting point- water in soil is so low that plant permanently wilts Available water - soil water between field capacity and permanent wilting point

45. 45 Soil pH Some plants thrive in acidic conditions, others basic liming- adding Ca or Mg to make soil basic basic soil can be made more acidic by adding S or N 2

46. 46 TEXT PHOT OS

47. 47 Fig. 5.4a

48. 48 Fig. 5.4b

49. 49 Fig. 5.8

50. 50 Fig. 5.11

51. 51 Fig. 5.16cd

52. 52 Fig. 5.18

53. 53 TA BL ES