Introduction More than 280,000 species of plants inhabit Earth today.

1. Introduction • More than 280,000 species of plants inhabit Earth today. • Most plants live in terrestrial environments, including deserts, grasslands, and forests. • Some species, such as sea grasses, have returned to aquatic habitats. • Land plants (including the sea grasses) are believed to have evolved from a certain green algae, called charophyceans.

2. Remember the Big 4 events in Plant evolution • Bryophytes, pteridiophytes, gymnosperms, ands angiosperms demonstrate four great episodes in the evolution of land plants: • the origin of bryophytes from algal ancestors • the origin and diversification of vascular plants • the origin of seeds • the evolution of flowers

3. Plant Structure & Organization • Cells make tissues, tissues make organs, organs make systems, systems make organisms • 5 Basic plant cell types • Parenchymal cells • Collenchymal cells • Sclerenchymal cells • Xylem cells • Phloem cells

4. 3 Cell types that make up all plant tissue • Parenchyma – perform most of metabolism (including photosynthesis) • Present throughout the plant • Collenchyma – help support growing parts of plants • Grouped in cylinders • Schlerenchyma – support in parts that are no longer growing • Have tough cell walls • 2 types just for support • Fibers • Scleroids

5. Plants have tissues: A.)Dermal tissue B.) Ground Tissue C.) Vascular tissue D.) Meristem = embryonic tissue

6. 3 tissue types that make up all plant organs • Dermal – single layer, closely packed, cover and protect the entire plant (epidermis and periderm) • Vascular – continuous throughout the plant • Transport tissue • 2 types • Xylem – moves water and minerals up (from roots) • Made of tracheids and vessel elements (dead cells) • Phloem - moves “food” down (from leaves) • Made of sieve tube members • Ground – anything that isn’t dermal or vascular (fills and stores) • Pith – inside the ring of the ground tissue • Cortex – Outside the ring of the ground tissue

7. Parts of a Plant - Shoots and Roots • Shoots (above ground: stems & leaves) • Produce food by photosynthesis • Carry out reproductive functions • Roots (below ground) • Anchor the plant • Penetrate the soil and absorb water and dissolved minerals • Store food • Roots, stems & leaves are all considered plant organs • We are going to look at these organs next

8. Angiosperm Body Plan EPIDERMIS • Ground tissue system • Vascular tissue system • Dermal tissue system VASCULAR TISSUES GROUND TISSUES SHOOT SYSTEM ROOT SYSTEM Figure 29.2 Page 506

9. Internal Anatomy : Stems • Vascular bundles (xylem and phloem) • Surrounded by ground tissue (xylem faces pith and phloem faces cortex) • Mostly parenchyma; some collenchyma and sclerenchyma for support

10. Leaf Structure:

11. Internal Anatomy :Leaf Structure UPPER EPIDERMIS cuticle PALISADE MESOPHYLL xylem SPONGY MESOPHYLL phloem LOWER EPIDERMIS Guard cell O2 & H20 one stoma CO2 Figure 29.16 Page 513

12. Adapted for Photosynthesis • Leaves are usually thin • High surface area-to-volume ratio • Promotes diffusion of carbon dioxide in, oxygen out • Leaves are arranged to capture sunlight • Are held perpendicular to rays of sun • Arranged so they don’t shade one another

13. Mesophyll:Photosynthetic Tissue • A type of parenchyma tissue • Cells have chloroplasts • Two layers in dicots • Palisade mesophyll - most photosynthesis takes place here • Spongy mesophyll - gas circulation • One layer in monocots

14. Leaf Veins: Vascular Bundles • Xylem and phloem; often strengthened with fibers • In dicots, veins are netlike • In monocots, they are parallel

16. Root Systems 2 types of root systems 1. fibrous – mat of thin roots just below soil surface 2. taproot – 1 thick vertical root with many lateral roots extending from it Figure 29.17 Page 514 Taproot system Fibrous root system

17. Internal Anatomy: Roots -Outermost layer is epidermis -Root cortex is beneath the epidermis -Endodermis, then pericycle surround the vascular cylinder (this is called the Casparian Strip) -the inner part called the stele contains the vascular tissue (xylem & phloem)

19. Root Hairs and Lateral Roots • Both increase the surface area of a root system and help in absorption • Root hairs are tiny extensions of epidermal cells • Lateral roots arise from the pericycle and must push through the cortex and epidermis to reach the soil new lateral root Figure 29.19 Page 515

20. Root Hairs Increase surface area for absorption

21. Flower Structure STAMEN (male reproductive part) CARPEL or pistil (female reproductive part) • Nonfertile parts • Sepals • Receptacle • Fertile parts • Male stamens • Female carpel (ovary) filament anther stigma style ovary OVULE (forms within ovary) petal (all petals combined are the flower’s corolla) sepal (all sepals combined are the flower’s calyx) receptacle Figure 31.3 Page 538

23. Two major groups (classes) of angiosperms

24. Kinds of Flowers • Perfect flowers • Have both male and female parts • Imperfect flowers • Are either male or female • Same plant may have both male and female flowers • Sexes may be on separate plants Kinds ofPlants • dioecious • Have both male and female parts • monoecious • Sexes on separate plants

25. Plant Growth: Meristems • Regions where cell divisions produce plant growth • Apical meristems – located at ends (roots and shoots) • Lengthen stems and roots • Responsible for primary growth • Lateral meristems • Increase width of stems • Responsible for secondary growth (thickening of roots and shoots) • 2 types • Vascular cambium • Cork cambium

26. Primary growth From tips of root From tips of shoots Growth in length Growth in to the environment Pattern can reflect environmental pressures Pericycle and auxiallary Provide branching Secondary growth Growth in width Not all plants have Monocots lack Comes from division of: Cork cambium Vascular cambium Produces structural strength Plant growth: perpetual meristems

27. Secondary Growth • Two lateral meristems • vascular cambium ~ produces secondary xylem (wood) and secondary phloem (diameter increase; annual growth rings) • cork cambium ~ produces thick covering that replaces the epidermis; produces cork cells; cork plus cork cambium make up the periderm; lenticels (split regions of periderm) allow for gas exchange; bark~ all tissues external to vascular cambium (phloem plus periderm)

28. Major Meristems

29. 3 growth zones • Zone of: • Cell division – includes the meristems, rapid cell division, new growth • Elongation – cells elongate • Maturation – cell differentiation occurs and cells become fuctionally mature

30. Tissue Differentiation – three primary meristematic tissues • Cells descended from apical meristem divide, grow and differentiate to form shoot’s primary tissue system Protoderm Ground meristem Procambium Epidermis Ground tissue Primary vascular tissue • From lateral meristems Vascular cambium Cork cambium Secondary vascular tissue Periderm & cork

31. Stem growth summary

33. Plant Transport 3 types • Uptake and loss of water and minerals from individual cells • Occurs through: • Osmosis – diffusion of water through the membrane • Water potential – the combined effect of solute concentration and cell wall pressure (remember, turgor pressure is the pressure against the cell wall from water) • Aquaporins – channels in plant cell walls designed for passage of water • Tonoplasts – surround the vacuoles to regulate molecules going in and out of the vacuoles

34. Transport of substances short distances (from cell to cell) • Is accomplished by: • Symplasts – cytoplasm connections between cells through plasmodesmata • Apoplasts – nonliving continuum that is formed by extracellular pathways through the continuous matrix of cell walls • Water flows through both symplasts and apoplasts

35. 3 major compartments and lateral transport! Apoplast- between cell walls between cells of the cortex Symplast- inside cells and thru plasmodesmata

37. Transport of sap within xylem and phloem (throughout the entire plant) A. Absorption of water and minerals by roots • Usually near root tips in root hairs • Mycorrhizae – symbiosis between roots and fungi • Helps roots absorb water and minerals • Water and minerals in root cortex must pass through endodermis to enter the stele and get to the xylem to be transported to the rest of the plant • Endodermis contains the “Casparian strip” which prevents subtances from going around or between the cells, therefore the water and minerals must pass through the endodermal cell to get into the vascular tissue

38. Casparian Strip • Prevents water and solutes from passing between cells into vascular cylinder • Water and solutes must flow through cells • Transport proteins control the flow • Allows plants to adjust the quantity and types of solutes absorbed from soil water exodermis root hair epidermis forming vascular cylinder cortex Casparian strip Figure 30.4   Page 526

39. Transport of sap within xylem and phloem (throughout the entire plant), continued B. Transport within the Xylem -Water is “pulled” through the plant in two ways • Root pressure – water flows into the roots cause positive pressure that forces the liquid up through the xylem • Cohesion-Tension mechanism – water lost through the leaves creates a negative pressure which draws water up through the xylem with the help of adhesion/cohesion - Transpiration – loss of water from leaves and other parts of plants in contact with air -especially through open stomata -plants have guard cells around stomata that open and close them to help control water loss

40. Transpiration-Cohesion-Tension Theory of how water moves UP xylem

42. 1.Transpiration evaporation of water from the leaf. 2.Cohesion water molecules stick together by hydrogen bonding because they are polar. 3. Tension is the pull as water molecule go to vapor because there is less water in the air. (Note: structure of xylem and how its function is related, how important xylem is to life on land both for support and transport, don’t forget lignin.) Factors in water movement up the stem by bulk transport

43. Xylem • Conducts water and dissolved minerals • Conducting cells are dead at maturity • hollow at maturity vessel member tracheids Figure 29.8  Page 509

45. Xylem! Cells Stacked!! Vascular Tissue

46. Root pressure is a PUSH! As solutes accumulate in xylem and water transpiration has stopped water continues to move in to dilute. Guttation is evidence

47. Guttation pushes water out of the tips of xylem-root pressure

48. Control of Stomata • When stomata are opened; the cells have a high solute content causing water to move in building up turgor pressure (the cells swell opened) • Close in response to water loss; ABA (abscisic acid - hormone) binds to receptors on guard cell membranes • calcium ions flow in and open gates for other solutes (chloride, potassium and malate) to flow out from cytoplasm to extracellular matrix • This causes a change in gradients and water moves out of guard cells, they collapse and close