1. Weed Biology and Identification-202
Target students:
M .Sc. Students in Weed Science
Lecture:
Dr. Majid AghaAlikhani (Ph.D.)
Academic position :
Associate Prof. of Tarbiat Modares University

2. Basic Parts of the Plant
Roots
Stems
Leaves
Flower

3. Shoot system
Root system

4. Shoot system
Lateral roots
Root system
Taproot

5. Shoot system
Leaves
Stem
Lateral roots
Root system
Taproot

6. Shoot system
Branch
Leaves
Stem
Lateral roots
Root system
Taproot

7. Apical bud
Lateral bud
Shoot system
Branch
Leaves
Stem
Lateral roots
Root system
Taproot

8. Apical bud
Node
Lateral bud
Internode
Node
Shoot system
Branch
Leaves
Stem
Lateral roots
Root system
Taproot

9. Roots 1. Anchor Plant 2. Absorb water and minerals
3. Translocate water and minerals to stem
4. Store Food

10. Root
Structure

11. Anchorage and support

12. Storage

13. Stems 1. Translocate water, minerals and food to the leaves
2. Support the leaves and display them to light
3. Store Food

14. Woody Dicot Stem Morphology

15. Transport and support.

16. Cactus stems store water, photosynthesize.

17. Stolons produce new individuals at nodes above ground.

18. Rhizomes produce new individuals at nodes below ground.

19. Tubers store carbohydrates.

20. Thorns provide protection.

21. Leaves 1. Make food through photosynthesis
2. Provide site of gas exchange
3. Store food

22. Sunlight
Shoot system
CO2
Transport of water, sugar, and nutrients through vascular tissue
Root system
Water
Nutrients
(such as N, P, K)

24. Make food through photosynthesis

25. Sloughed-off root cap cells
(a) Longitudinal section of root segment
Primary Growth
Lateral root
Cellular Maturation
Zone of
Root hair
(b) Close-up of root tip
Vascular tissue
Cellular Elongation
Zone of
Ground tissue
Epidermal tissue
Zone of
Cellular Division
Apical mersitem
Sloughed-off root cap cells
mucilage
Root cap

26. Flowers 1. Contain organs for specialized sexual production
2. Produce seeds and fruit

27. Different type of Roots
A. Tap Root
Continuation of the primary root
Ideal for anchorage
Penetration is greater for water
Storage area for food made by photosynthesis

28. ARE YOU PAYING ATTENTION?
THERE JUST MAY BE A QUIZ!!!

29. Different type of Roots
B. Fibrous Roots
Many finely branched secondary roots
Shallow roots cover a large area
More effective absorption of water and minerals
Roots hold the soil to prevent erosion

30. Different type of Roots
C. Aerial roots
Clinging air roots
Short roots that grow horizontally from the stems
Roots that fasten the plant to a support
Absorptive air roots

31. Different type of Roots
Adventitious Roots
Develop in places other than nodes
Can form on cuttings and rhizomes

32. Roots
Root hairs:
Tiny one celled hair like extensions of the epidermal cells located near the tips of the roots where vascular tissues have formed.
Increase surface area
Absorb water and minerals from soil

33. Absorbing water and nutrients

34. Specialized Stems A. Corm (gladiolus, crocus) underground
Solid, fleshy, scale covered

35. WAKE UP!!!!!!!!!!!!
DON’T FALL ASLEEP
PAY ATTENTION!
THIS MEANS YOU!!!

36. Specialized Stems B. Bulb (tulips, lillies, onions)
Layers of fleshy scales that overlap each other
Underground stem

37. Specialized Stems C. Tuber (potato, caladium) Food storage area
Short, thick underground stem

38. Specialized Stems D. Crown (African Violets, fern)
Closely grouped stems or plantlets
Just above ground or just below

39. Specialized Stems E. Spurs (pear and apple trees)
Short sems found on woody plant limbs adapted for increased production of fruits

40. Specialized Stems F. Rhizomes (iris, lily of the valley)
Underground stems that produce roots on the lower surface and extend leaves and flower shoots above the ground

41. Specialized Stems G. Stolon (Strawberry, airplane plant)
Stem that grows horizontally above the soil surface

42. Principal Tissues of the Leaf
Epidermis
Cuticle
Waxy substance covers the leaves and stems
Waterproof layer that keeps water in plants

43. Principal Tissues of the Leaf
Epidermis (cont)
Stomata
Openings in the epidermis mainly located on underside of leaves
Exchange of gases

44. Principal Tissues of the Leaf
Epidermis (cont)
Guard Cells
Two cells located on each side of stomata
Open and closes stomata

45. Principal Tissues of the Leaf
Mesophyll layer
Palisade mesophyll
Primary site of photosynthesis
Spongy mesophyll
Contains air and chloroplasts
Site of photosynthesis and gas exchange

46. Principal Tissues of the Leaf
Veins or vascular bundles
In spongy mesophyll
Phloem tissues conduct food from photosynthesis to rest of plant
Xylem tissues conduct water and minerals up to cells in leaves and stems

47. Parts of the Flower Sepals Outer covering of the flower bud
Protects the stamens and pistills when flower is in bud stage

48. Parts of the Flower Petals Brightly colored
Protects stamen and pistills
Attracts pollinating insects

49. Parts of the Flower Stamens Male Reproductive part
Anther-produces pollen
Filament-supports the anther

50. Parts of the Flower Pistil Female reproductive part Ovary
Enlarged portion at base of pistill
Produces ovules which develop into seeds
Stigma
Holds the pollen grains

51. Parts of the Flower Style Connects the stigma with ovary
Supports the stigma so that it can be pollinated

52. Complete and Incomplete Flowers
Complete: have all four main parts
Sepals
Petals
Stamens
Pistils