Anatomy & Growth of Angiosperms

1. Anatomy & Growth of Angiosperms

2. Two plant groups: monocots & eudicots

3. A. Uniqueness of Plants I. Introduction http://www.fugu-sg.org/~elia/cambodia/templesfacesweb/pages/A3_Embracing_Roots.htm

4. B. Forces for Change • 1. Genetics • 2. Environment – two time scales: • a. Long-term: accumulation of adaptations that • enhanced survival & reproduction (evolution by • natural selection) • b. Short-term: plasticity = wide range of • phenotypes for each genotype. Allows plants to • adjust to changing environment (ex. Shorter plant in • dry year so that it can still reproduce)

5. Cells Muscle cell Parenchyma cell Tissues Muscle tissue Dermal tissue Organs Heart Leaves Systems Circulatory system Shoot system

6. II. Plant Organs: Roots, Stems, Leaves A. Roots 1. Functions a. Collect water & minerals from soil b. Anchor plant c. Store food (carb’s from photosynthesis) to be used for flowering & fruiting d. Covered with root hairs – increases surface area for absorption

8. Fig. 35.2

9. Fig. 35.4 2. Types a. Prop root c. Aerial strangler root b. Storage root d. Buttress root e. Pneumatophore

10. B. Stems/shoots • 1. Functions • a. Support, transport • b. Some photosynthesis • 2. Two types of shoots • a. Vegetative – leaves only • b. Reproductive – produces flowers

12. 3. Two parts of the stem: a. Node – point of leaf attachment b. Inter-node – stem segments between nodes

14. 4. Buds Apical dominance = the presence of an apical bud inhibits the growth of axillary buds. - remove or depress apical bud, axillary buds begin to grow. a. Terminal bud – contains a shoot apical meristem; shoot growth is concentrated here b. Axillary buds – in angle (axil) between leaf & branch, contain meristem with potential to become a vegetative shoot. Mostly dormant.

15. Fig. 35.2

16. 5. Modified Shoots (stems): a. Stolons – above-ground runners b. Rhizomes – below-ground runners Asexual, vegetative propagation c. Bulbs – swollen underground shoots d. Tubers – swollen rhizomes Stores food for later growth

17. Fig. 35.5

18. C. Leaves– main photosynthetic organs 1. Parts a. Petiole b. Blade http://www.knotweed.co.uk/japknot_Info.htm

19. 2. Types Compound, doubly compound – why??

20. a. Tendrils Fig. 35.7 3. Modified leaves b. Spines c. Succulents

21. III. Plant Tissue Fig. 35.8

22. A. Dermal or Epidermis 1. Characteristics a. single layer of tightly packed cells covering the young parts of the plant. b. Functions in protection c. Root hairs are specialized epidermal extensions d. Secretes waxy cuticle of the leaf

24. B. Ground 1. Characteristics a. Fills the space between dermal and vascular tissue systems. b . Diverse functions: Photosynthesis, storage, & support pith In eudicots stems: cortex

25. C. Vascular 1. Characteristics a. function in transport between roots & shoots, and structural support of plant 2. Types a. Xylem: H2O & minerals transported up to shoot system b. Phloem: Food transported to roots & non- photosynthetic parts such as the flowers

26. IV. The Plant Cell Fig. 7.8

27. A. Generalized Same as animals, except: 1. No lysozomes (digestive organelle) 2. Cell walls: maintains shape, structural support, protects from damage. Made of cellulose, protein, & sometimes lignin 3. Chloroplasts 4. Vacuole – storage, waste breakdown, growth! 5. Plasmodesmata – holes in cell wall, creates channels to connect cytoplasm of adjacent cells

28. B. Plant Cell Categories 1. Parenchyma 4. Water-conducting cells of the xylem 3. Sclerenchyma 5. Sugar-conducting cells of the phloem 2. Collenchyma

29. 1. Parenchyma a. Characteristics i. Least specialized cell. Can differentiate into other cell types ii. Primary cell walls only - thin and flexible iii. Lack secondary plant cell walls iv. Most metabolically active – lots of chloroplasts for PSN (PhotoSyNthesis) v. Starch, carbohydrate production & storage in stems

30. 2. Collenchyma a. Characteristics i. Primary walls are unevenly thickened ii. Usually lack secondary walls. iii. Usually grouped in strands to support young parts of plants without restraining growth iv. Flexible, elongate with growing shoots

31. 3. Sclerenchyma a. Characteristics i. Function in mechanical support ii. Have rigid and thick secondary walls strengthened with lignin. iii. May be dead at functional maturity iv. Cell walls left behind as skeleton

32. Lignin:

33. 3. Sclerenchyma b. Two types, both function in support: i. Fibers - long, slender, tapered cells occurring in bundles. ii. Sclereids - short, irregularly-shaped. Ex. hard seed coats

35. Fig.35.9

36. 4. Water/Mineral conducting cells of the xylem: i. Tracheids a. 2 types: tracheids & vessel elements Cells that are long, thin tapered cells having lignin-hardened secondary cell walls with pits. They are dead at maturity in which water flows from cell to cell (laterally) through the pits in the cell walls 1o wall only Their role is in a support function ii. Vessel Elements These cells are wider, shorter and arranged end-to-end to form tubes. Their end walls are perforated to allow for the free flow of water and are more efficient as water conductors than tracheids.

37. Fig. 35.9

38. 5. Sugar-conducting cells of the phloem a. 2 types i. Sieve-tube members: Chains of cells arranged end-to-end, Alive at functional maturity, Lack a nucleus, ribosomes, & vacuole, and Cells separated by perforated sieveplates – allow sugar movement. ii. Companion cells: Load sugars into the sieve tube member, Nucleus and ribosomes also serve the sieve-tube member.

39. Fig. 35.9

40. V. Growth & Development http://www.cneccc.edu.hk/subjects/bio/album/Chapter20/PLANT_GROWTH.html

41. A. Definitions 1. Development is the sum of all the changes 2. Cell Division 3. Morphogenesis

42. B. Processes of plant cellular development: 1. Cell Growth a. Cell division (Mitosis) in itself does not mean an increase in growth. b. Cell division yields no expansion of size. c. Cell elongation increases growth.

43. Fig. 35.22

44. 2. Cell elongation a. due to water uptake b. Direction of expansion = perpendicular to alignment of cellulose microfibrils in cell wall c. Enzymes weaken cross-link between microfibrils, allowing cell to expand.

45. Fig. 35.24

46. Fig. 39.8

47. 3. Morphogenesis a. The coordinated arrangement of cells into tissues & organs b. Pattern formation – development of specific structures in specific places (e.g. Flowers born on the terminus of branches as opposed to leaf axils. c. Depends on: i. Positional information – chemical signals from surrounding cells indicate the cell’s position on plant ii. Polarity of the plant, asymmetrical cell divisions iii. Both affect the transcription of homeotic genes

48. 4. Cellular Differentiation • a. Transformation of genetically identical cells into cells with • diverse biochemical and structural features. How? • i. Selective transcription of appropriate genes • ii. How? Chapters 18 & 39 • iii. Flow of Info

49. DNA Replication Transcription RNA Energy Amino Acids Translation Polypeptide Additional Materials Energy Modification Functional Protein The Flow of Information

50. b. Regulation i. at transcriptional level ii. Regulation at translational level iii. Regulation at post translational level iv. Hormonal controls v. Regulation at substrate level vi. Regulation by environmental signals: light, gravity,…..