1. Chapter 33: Stems and Plant Transport Chapter 34: Roots

2. Stem functions Support – leaves and reproductive parts – Photosynthesis/access to pollination Internal transport Produce new living tissue Other jobs – Asexual reproduction – Photosynthesis – Store starch

3. Herbaceous dicot stems Epidermis – protection, cuticle (cutin) Cortex – inside epidermis, ground tissue – Parenchyma – photosynthesis / storage – Collenchyma + sclerenchyma - support Vascular bundles – conduction, support – Circle arrangement – Xylem (inner), phloem (outer) – Vascular cambium btw. Xylem and phloem

4. Pith – center of stem – Large parenchyma – storage Because of arrangement of vascular tissues in bundles, there is no distinct separation of cortex + pith between vascular bundles Arrangement of parenchyma btw. Bundles = pith rays

5. Fig. 35-17a Sclerenchyma (fiber cells) PhloemXylem Ground tissue connecting pith to cortex Pith Cortex Epidermis Vascular bundle 1 mm Cross section of stem with vascular bundles forming a ring (typical of eudicots) (a) Dermal Ground Vascular Key to labels

6. Monocot stems Epidermis – cuticle Vascular bundles – scattered – Xylem (inside), phloem (outside) – Bundle sheath - sclerenchyma No distinct cortex or pith – Ground tissue – same functions as dicot stem No lateral meristems – Primary growth only, no wood/bark

7. Fig. 35-17b Ground tissue Epidermis Key to labels Cross section of stem with scattered vascular bundles (typical of monocots) Dermal Ground Vascular (b) Vascular bundles 1 mm

8. Woody dicot + conifer stems Secondary growth – 2 lateral meristems (replace primary tissues) – Pith in center – Vascular cambium Secondary xylem – wood Secondary phloem – inner bark – Cork cambium Cork cells + cork parenchyma Periderm (outer bark) = cork cambium, cork cells and cork parenchyma – Replaces epidermis

9. Woody stems starts with same primary tissues in vascular bundles Secondary growth = many changes – Vascular cambium becomes continuous ring Produce cells inside (sec. xylem), outside (sec. phloem) Primary tissues become separated from each other Sec. tissues take over functions of primary tissues (vertical movement of substances)

10. Fig. 35-11 Shoot tip (shoot apical meristem and young leaves) Lateral meristems: Axillary bud meristem Vascular cambium Cork cambium Root apical meristems Primary growth in stems Epidermis Cortex Primary phloem Primary xylem Pith Secondary growth in stems Periderm Cork cambium Cortex Primary phloem Secondary phloem Pith Primary xylem Secondary xylem Vascular cambium

11. Fig. 35-19a3 Epidermis Cortex Primary phloem Vascular cambium Primary xylem Pith Primary and secondary growth in a two-year-old stem (a) Periderm (mainly cork cambia and cork) Secondary phloem Secondary xylem Epidermis Cortex Primary phloem Vascular cambium Primary xylem Pith Vascular ray Secondary xylem Secondary phloem First cork cambium Cork Growth Cork Bark Most recent cork cambium Layers of periderm

12. – Lateral movement through rays = chains of parenchyma that radiate out from center of woody stem or root Formed by vascular cambium

13. – Cork cambium – makes periderm (replaces epidermis) Continuous ring or series of overlapping arcs Different cork cambia + rates of division  different bark types Lenticels for gas exchange New tissues in 2 directions – Outside – cork cells; dead at maturity; protection – Inside – cork parenchyma; store water/starch

14. Wood terms Sapwood – functional sec. xylem Heartwood – older wood, center Hardwood – flowering plants Softwood – conifers, lack fibers, vessel elements Knot – embedded dead branch Annuals rings – concentric circles in cross section – Temperate zone only – age (spring and summer growth) – Spring wood – more water, larger cells – Summer wood – less water, narrow cells

15. Fig. 35-19b Secondary phloem Vascular cambium Secondary xylem Bark Early wood Late wood Cork cambium Cork Periderm 0.5 mm Vascular ray Growth ring Cross section of a three-year- old Tilia (linden) stem (LM) (b) 0.5 mm

16. Fig. 35-22 Growth ring Vascular ray Secondary xylem Heartwood Sapwood Bark Vascular cambium Secondary phloem Layers of periderm

18. Internal Transport Xylem – Roots only upward to stems, leaves, flower, fruits, seeds – Water and dissolved nutrient minerals Phloem – Leaves to parts throughout plant – Downward or upward – Sugar in solution

19. Xylem transport – xylem sap No energy Path of water – Soil  root tissues  root xylem  stem xylem  leaf xylem  leaf mesophyll  atmosphere 2 mechanisms for upward flow: – Root pressure – Tension (transpiration) – cohesion model

20. Root pressure Water – osmosis – soil to root More water = more pressure at root Water is pushed upward

21. Tension (transpiration)) – cohesion Model Water is pulled up plant by tension (caused by transpiration pull) Water column can’t be broken – Cohesion = water-water (H bonds) – Adhesion = water-xylem cells (H bonds)

22. Phloem Transport – phloem sap Glucose  sucrose (glucose + fructose) in solution Pressure – Flow Mechanisms – Source (excess sugar)  sink (area of storage- roots, fruits, seeds, apical meristems) – Pressure gradient – Sugar in leaf mesophyll  companion cell  sieve tube member by active transport (ATP) – Then  water moves from xylem to sieve tubes by osmosis  increases pressure

23. – At sink – sugar unloaded from sieve tube – Water follows – Decrease in pressure

24. Ch. 34 Roots Functions – Anchor – Absorb water + dissolved nutrient minerals (nitrates, phosphates, sulfates) – storage

25. Herbaceous Dicot roots Epidermis – no cuticle, has root hairs  increase absorption Cortex – loose parenchyma – Storage – Spaces – water path, aeration – Endodermis – inner layer of cortex; regulates movement of minerals into xylem

26. Stele – center or dicot root; central cylinder of vascular tissues – Pericycle – outermost layer of stele, just inside endodermis; makes lateral roots – Xylem – centermost of stele; “xylem arms” – Phloem – between xylem arms

27. Fig. 35-14a1 Root with xylem and phloem in the center (typical of eudicots) (a) 100 µm Epidermis Cortex Endodermis Vascular cylinder Pericycle Xylem Phloem Dermal Ground Vascular Key to labels

28. Fig. 35-14a2 Vascular Ground Dermal Key to labels Root with xylem and phloem in the center (typical of eudicots) (a) Endodermis Pericycle Xylem Phloem 50 µm

29. Fig. 35-15-3 Cortex Emerging lateral root Vascular cylinder 100 µm Epidermis Lateral root 3 2 1