BOT3015L Biology of Flowering Plants Anatomy Seedlings, Meristems, Stems, and Roots

1. BOT3015LBiology of Flowering PlantsAnatomySeedlings, Meristems, Stems, and Roots Presentation created by Danielle Sherdan All photos from Raven et al.Biology of Plants except when otherwise noted

2. Today • Review seeds and the life cycle of plants • Seed germination • Roots and root meristem • The three primary tissues • Specialized cells in primary root tissues • Interesting examples of root function and adaptations • Shoot and shoot meristem • Review seeds and the life cycle of plants • Seed germination • Roots and root meristem • The three primary tissues • Specialized cells in primary root tissues • Interesting examples of root function and adaptations • Shoot and shoot meristem

3. Life cycles From Outlaw’s lecture series

4. Floral structure Gametophytes Today Angiosperm life cycle From Outlaw’s lecture series

5. Monocot seed development typical monocot (maize) seed with ovary wall (pericarp) Monocots have one cotyledon (scutellum in grasses) that matures during germination Source of nutrition for seed germination: endosperm (compare to dicot) Maize fruit and seed

6. mature Dermal Vascular Cortex or Ground dicot - two cotyledons Dicot seed development immature Three tissue systems: All cells of the primary growth in dicots are part of these three systems and originate at meristems . . . A reminder that endosperm is formed in all angiosperms, but does not persist in dicots. In dicots, cotyledons are the primary source of nutrients for germination.

7. Today • Review seeds and the life cycle of plants • Seed germination • Roots and root meristem • The three primary tissues • Specialized cells in primary root tissues • Interesting examples of root function and adaptations • Shoot and root meristem

8. Seed germination What causes a seed to resume growth? What is growth? Broadly, where do the energy and basic elements required for growth come from? What observations did you make while germinating seeds? Plants-In-Motion Time-lapse videos of plant growth and response

9. Dicot germination and seedling An example of epigeous (epi=above, geo=earth) germination

10. Dicot germination and seedling An example of hypogeous (hypo=below, geo=earth) germination

11. Monocot germination and seedling

12. Today • Review seeds and the life cycle of plants • Seed germination • Roots and root meristem • The three primary tissues • Specialized cells in primary root tissues • Interesting examples of root function and adaptations • Shoot and shoot meristem

13. Rootthe first structure to emerge from the germinating seed Typical dicot Taproot persists and grows deep into the ground Typical monocot Taproot does not persist and adventitious roots originate from the shoot Notice the high surface volume: area ratio

14. Tap Root vs. Fibrous Root What are the functions of roots? From Outlaw lecture Typical of a dicot Typical of a monocot

15. Root apical meristem Organization of the plant body Meristem = group of perpetually “embryonic” cells Apical = at the tip (of the root, the shoot, including laterals)

16. The rootcap and mucigel protect the root apical meristem as it pushes through the soil Mucigel

17. Today • Review seeds and the life cycle of plants • Seed germination • Roots and root meristem • The three primary tissues • Specialized cells in primary root tissues • Interesting examples of root function and adaptations • Shoot and shoot meristem

18. All cells of primary growth are from one of three primary tissues

19. Diagram of major parts of primary dicot plant body Ground tissue is throughout the plant body

20. Ground tissue of typical dicot root and shoot Root Buttercup (Ranunculus) Shoot Alfalfa (Medicago)

21. All cells are from one of three primary tissues

22. Diagram of major parts of primary dicot plant body Vascular tissue is throughout the plant body

23. Vascular tissue of typical dicot root Root Buttercup (Ranunculus)

24. Vascular tissue of typical dicot shoot Shoot Alfalfa (Medicago)

25. All cells of primary growth are from one of three primary tissues

26. Diagram of major parts of primary dicot plant body Dermal tissue is throughout the plant body

27. Ground tissue of typical dicot root and shoot Root Buttercup (Ranunculus) Shoot Alfalfa (Medicago)

28. Specialized dermal cells in the shoot The structure of the leaf and aspects of stomatal physiology will be topics of study next week

29. Specialized epidermal cellsVenus flytrap

30. Today • Review seeds and the life cycle of plants • Seed germination • Roots and root meristem • The three primary tissues • Specialized cells in primary root tissues • Interesting examples of root function and adaptations • Shoot and shoot meristem

31. Root Hairs—a special feature of roots (a) Bentgrass (Agrostis) Radish (Raphanus)

32. Cell Elongation Cell Division Root Hairs—a special feature of roots (b)

33. Root Hairs—a special feature of roots (c) More than with shoots, elongation growth is restricted to very near (~1.5 mm) the root tip; otherwise, elongation would tear off lateral appendages. Root hairs increase surface area.

34. Typical dicot root Root Buttercup (Ranunculus)

35. The endodermis Casparian Strip—a band of hydrophobic material (mostly suberin) that is impregnated in the wall, preventing apoplastic transport. From Outlaw’s lecture

36. The endodermis Pathways for entry into xylem transport: all require that the solute be transported into the symplast (because the apoplast is discontinuous at the endodermis). Then, solutes are excreted into the apoplast interior to the endodermis. Apoplast Symplast From Outlaw’s lecture

37. Typical dicot root Root Buttercup (Ranunculus)

38. The cambium (perpetually meristematic layer between xylem and phloem) divides mitotically, producing either: A secondary xylem cell to the inside and a replacement cambial cell. OR A secondary phloem cell to the outside and a replacement cambial cell. Secondary Growth (root) Example cross section of the dicot root in primary growth Secondary growth rare in monocots From Outlaw’s lecture

39. The pericycle Ordinarily, lateral roots arise in the pericycle. But roots can arise adventitiously, too. (Adventitious simply means arising in an unusual location.) Salix (Salicaceae family) From Outlaw’s lecture

40. Today • Review seeds and the life cycle of plants • Seed germination • Roots and root meristem • The three primary tissues • Specialized cells in primary root tissues • Interesting examples of root function and adaptations • Shoot and shoot meristem

41. InterestingExamples Mangrove (a dicot) Support roots in the marsh habitat. From Outlaw’s lecture

42. Epidermal layers InterestingExamples Orchid (a monocot) Aerial roots absorb water from the air and have a multi-layered epidermis for protection and reduced water loss Cross section of root

43. InterestingExamples Flower pot plant (an epiphyte) Modified leaves form hollow containers that roots grow into and that collect rainwater and debris. Many ants associate with these plants, likely adding to nitrogen supply

44. Today • Review seeds and the life cycle of plants • Seed germination • Roots and root meristem • The three primary tissues • Specialized cells in primary root tissues • Interesting examples of root function and adaptations • Shoot and shoot meristem

45. The shoot What are the functions of the shoot?

46. Primary tissues differently organized in angiosperm shoots Typical of dicots Typical of monocots

47. Primary tissues differently organized in angiosperm shoots Example dicot stem cross section vascular bundles in ring with defined pith and cortex Shoot Alfalfa (Medicago)

48. Primary tissues differently organized in angiosperm shoots Example monocot stem cross section vascular bundles scattered Maize (Zea)

49. Apical Meristems both have the three primary tissues Root Shoot Radish (Rafarus) Lilac (Syringa)

50. Block Diagram of Typical Shoot Apical Meristem Lilac (Syringa) Primary meristems give rise to primary tissues Modified from Outlaw’s lecture