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Plant structure, growth development
- 2. I. Overview –Plant Systems II. Plant cell types & tissues Cell Types: Parenchyma, Collenchyma, Sclerenchyma A. Dermal B. Vascular C. Ground III. Plant organs A. Roots B. Stems C. Leaves IV. Plant Growth A. Meristems B. Primary vs. secondary V. Preparation for next lecture
- 3. Plant Structure, Growth,Development Plants are notably different from animals: 1. SA:V ratio 2. Mobility 3. Growth 4. Response to environment 5. Cell structure
- 4. Setting the scene- animal bodies Cells Tissues Organs Systems
- 5. Plant “bodies” Three BasicPlant Organs: Roots, Stems, and Leaves (also flowers, branches) Plants, like multicellular animals, have organs composed of different tissues, which in turn are composed of cells Shoot system Leaf Stem Root system
- 6. • Each plantorgan has dermal, vascular, and ground tissues • Each of these three categories forms a system – Roots – Shoots – Vascular Plant Tissues Dermal tissue Ground tissue Vascular tissue
- 7. 1) Dermal Tissues •Outer covering • Protection 3) Ground Tissues • “Body” of plant • Photosynthesis; storage; support 2) Vascular Tissues • “Vessels” throughout plant • Transport materials Plant Tissues Three basic cell types: Parenchyma Collenchyma Sclerenchyma
- 8. What type oftissue transports fluids in plants? A. Dermal B. Roots C. Vascular D. Stems E. Ground
- 9. Plant Cell Types Plantcell structure recap Cell wall, plasmodesmata Primary wall (some have secondary wall), middle lamella
- 10. Plant Cell Types 1)ParenchymaParenchyma (most abundant): • plant metabolism: Photosynthesis; hormone secretion; sugar storage Flexible, thin-walled cells; living renchyma cells in odea leaf,(w/chloroplasts) • thin wall permeable to gasses • large central vacuole • able to divide and differentiate
- 11. 2) CollenchymaCollenchyma: Thick-walled (uneven);living • Offers support (flexible & strong) • Able to elongate • Grouped in strands, lack secondary wall Collenchyma cells sunflower Plant Cell Types
- 12. 3) SclerenchymaSclerenchyma: Thick,hard-walled; Dead • Offer support (e.g. hemp fibers; nut shells) • Thick secondary walls with lignin • Rigid (cannot elongate) • Two types – sclereids and fibers Sclereid cells in pear (LM) Fiber cells in ash tree l wall Plant Cell Types
- 13. Which is aplant cell type? A. secondary B. vascular C. ground D. collenchyma E. leaves
- 14. Dermal Tissue System(Covering of Plant): 1) Epidermal Tissue (epidermis): Outer layer Cuticle: Waxy covering - reduces evaporation/ predation Root Hairs: extended root surface - Increase absorption Plant Tissues - Dermis 2) Peridermal Tissue (periderm): • Only in woody plants (“bark = dead cells”) • Protection; support
- 15. Plant Tissues -Dermis Special Dermal Cells – Trichomes & Root hairs • Trichomes – Hairlike outgrowths of epidermis – Keep leaf surfaces cool and reduce evaporation • Roots hairs – Tube extensions from epidermal cells – Greatly increase the root’s surface area for absorption
- 16. Guard cells Stoma Epidermal cell Guardcells Stomata Epidermal cell Guard cells Stoma Epidermal cell Guard cells Stomata Epidermal cell 4 µm 200 µm 71 µm a. c. b. Plant Tissues - Dermis Paired sausage-shaped cells Flank a stoma – epidermal opening • Passageway for oxygen, carbon dioxide, and water vapor Special Dermal Cells – Guard Cells
- 17. Vascular tissues madeup of multiple cell types: Plant Tissues - Vascular Arranged in multiple bundles or central cylinder Xylem – water and nutrients Phloem – dissolved sugars and metabolites
- 18. 1) Xylem (deadat maturity): water and minerals roots to shoots Plant Tissues - Vascular A) Tracheids: Narrow, tube-like cells B) Vessel Elements: Wide, tube-like cells C) Fibers
- 19. 1) Xylem: Plant Tissues- Vascular Tracheids: - Most vascular plants - Long, thin, tapered ends, lignified secondary walls - Water moves cell to cell through pits Vessel elements: - Wider and shorter - Perforation plates ends of vessel elements - water flows freely though perforation plates
- 20. A) Sieve Tubes:Wide, tube-like cells B) Companion Cells: support and regulate sieve tubes 2) Phloem (living at maturity) cells: Plant Tissues - Vascular
- 21. - Moves water,sugar, amino acids & hormones 2) Phloem (living at maturity) Plant Tissues - Vascular Sieve tube elements/members • Living parenchyma • Long narrow cells stack end to end • Pores in end walls (sieve plates) • Lack most cellular structures including: • Distinct vacuole, Some cytoskeletal elements, Nucleus, Ribosomes Companion Cells: • Adjacent to every sieve tube element • Non-conducting. • Regulate both cells • Connected by numerous plasmodesmata
- 22. Dicots Monocots Vasculature -Comparisons Monocots and dicots differ in the arrangement of vessels in the roots and stems Root Stem
- 23. Plant Tissues –Ground Tissue • Tissues that are neither dermal nor vascular are ground tissue • Ground tissue internal to the vascular tissue is pith; ground tissue external to the vascular tissue is cortex • Ground tissue includes cells specialized for storage, photosynthesis, and support
- 24. • Roots needsugars from photosynthesis; • Shoots rely on water and minerals absorbed by the root system Roots - Overview • Root Roles: - Anchoring the plant - Absorbing minerals and water - Storing organic nutrients
- 25. Taproots: Fibrous roots: Typicalof dicots, primary root forms and small branch roots grow from it In monocots mostly, primary root dies, replaced by new roots from stem Roots - Comparisons
- 26. Roots – Structureand Development • Four regions: – Root cap Protection, gravity detection – Zone of cell division Mitotic divisions – Zone of elongation Cells lengthen, no division – Zone of maturation Cells differentiate, outer layer becomes dermis
- 27. Roots – Structureand Development In maturation zone, Casparian strip forms – waterproof barrier material surrounding vasculature
- 28. Roots – Structureand Development 1250 µm Epidermis Primary phloem Primary xylem Pith MonocotEudicot Endodermis Cortex Epidermis Primary xylem Pericycle Primary phloem 48 µm 385 µm 8 µm Endodermis Location of Casparian strip Endodermis Location of Casparian strip Cortex Pericycle
- 29. Prop roots “Strangling” aerial roots Storageroots Buttress roots Pneumatophores Roots – Many Plants Have Modified Roots Water storage
- 30. Stem: an organmade of – An alternating system of nodes, points at which leaves attach – Internodes, stem length between nodes Stems - Overview • Axillary bud - structure that can form a lateral shoot, or branch • Apical/terminal bud - located near the shoot tip, lengthens a shoot • Apical dominance maintains dormancy in most nonapical buds Apical bud Node Internode Apical bud Shoot system Vegetative shoot Axillary bud Stem
- 31. Phloem Xylem Sclerenchyma (fiber cells) Groundtissue connecting pith to cortex Pith Cortex 1 mm Epidermis Vascular bundle Cross section of stem with vascular bundles forming a ring (typical of eudicots) a) Key to labels Dermal Ground Vascular Cross section of stem with scattered vascular bundles (typical of monocots) (b) 1 mm Epidermis Vascular bundles Ground tissue • In most monocot stems, the vascular bundles are scattered throughout the ground tissue, rather than forming a ring Vasculature - Stems Dicot Monocot
- 32. Stems – Structureand Development • Stems have all three types of plant tissue • Grow by division at meristems – Develop into leaves, other shoots, and even flowers • Leaves may be arranged in one of three ways
- 33. Rhizomes Bulbs Storage leaves Stem Stolons Stolon Tubers Stems –Many Plants Have Modified Stems
- 34. The leaf isthe main photosynthetic organ of most vascular plants Leaves - Overview Shoot system Leaf Blade Petiole Leaves generally have a flattened blade and a stalk called the petiole, which joins the leaf to a node of the stem
- 35. Leaves – Structureand Development • Leaves are several layers thick – each with different cell types
- 36. Leaves – Structureand Development • Most dicots have 2 types of mesophyll – Palisade mesophyll high photosynthesis – Spongy mesophyll air spaces for gas & water exchange • Monocot leaves have 1 type of mesophyll
- 37. Leaves • Leaf epidermiscontains stomata - allow CO2 exchange • Stomata flanked by two guard cells, control open vs. closed Key to labels Dermal Ground Vascular Cuticle Sclerenchyma fibers Stoma undle- heath ll Xylem Phloem a) Cutaway drawing of leaf tissues Guard cells Vein Cuticle Lower epidermis Spongy mesophyll Palisade mesophyll Upper epidermis Guard cells Stomatal pore Surface view of a spiderwort (Tradescantia) leaf (LM) Epidermal cell (b) 50µm100µm Vein Air spaces Guard cells Cross section of a lilac (Syringa)) leaf (LM) (c)
- 38. Most dicots have branch-likeveins and palmate leaf shape Monocots have parallel leaf veins and longer, slender blades Leaves - Comparisons Monocots and dicots differ in the arrangement of veins, the vascular tissue of leaves
- 39. Tendrils Spines Storage leaves Reproductive leaves Bracts Leaves –Plants have modified leaves for various functions
- 40. Plant Classification –Monocots vs. Dicots Basic categories of plants based on structure and function
- 41. Plant Growth: 1) Indeterminate:Grow throughout life 2) Growth at “tips” (length) and at “hips” (girth) Growth patterns in plant: 1) Meristem Cells: Dividing Cells 2) Differentiated Cells: Cells specialized in structure & role • Form stable, permanent part of plant Plant Growth
- 42. 1) Primary Growth: 1)Increased length 2) Specialized structures (e.g. fruits) 2) Secondary Growth: Responsible for increases in stem/root diameter • Apical Meristems: Mitotic cells at “tips” of roots / stems • Lateral Meristems: Mitotic cells “hips” of plant Plant Growth girth length
- 43. Shoot apical meristemLeaf primordia Young leaf Developing vascular strand Axillary bud meristems Plant Growth
- 44. Shoot tip (shoot apicalmeristem 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 Plant Growth Two lateral meristems: vascular cambium and cork cambium
- 45. Stem – SecondaryGrowth: • thicker, stronger stems Vascular Cambium: between primary xylem and phloem primary phloem vascular cambium primary xylem epidermis cortex pith primary xylem primary phloem dividing vascular cambium Plant Growth Produces inside stem: A) Secondary xylem - moves H2O, inward B) Secondary phloem - moves sugars, outward
- 46. Plant Growth primary phloem dividing vascular cambium new secondary xylem new secondary phloem primary xylem secondary phloem primaryphloem vascular cambium primary xylem secondary xylem pith cortex Secondary growth Vascular Cambium: Vascular cambium Growth Secondary xylem After one year of growth After two years of growth Secondary phloem Vascular cambium X X X X X X P P P P C C C C C C C C C C C C C
- 47. A cross sectionof what tissue is pictured? A. Monocot root B. Dicot root C. Monocot stem D. Dicot stem
- 48. Things To DoAfter Lecture 5… Reading and Preparation: 1. Re-read today’s lecture, highlight all vocabulary you do not understand, and look up terms. 2. Ch. 35 Self-Quiz: #1, 3, 6, 7 (correct answers in back of book) 3. Read chapter 35, focus on material covered in lecture (terms, concepts, and figures!) 4. Skim next lecture. “HOMEWORK” (NOT COLLECTED – but things to think about for studying): 1. Compare and contrast monocots and dicots. 2. List the different types of plant cells and describe which tissues and organs they make up, including roles for each organ. 3. Explain the different between apical and lateral meristems and how growth occurs. 4. Discuss the composition of bark and it’s function for plants (do all plants have this tissue?)
Editor's Notes
- #11 FIGURE 42-5 The structure of ground tissue (a) Parenchyma cells are living and serve many functions. They have thin, flexible primary cell walls. These parenchyma cells are used for starch storage in a potato. (b) Collenchyma cells are living and have thickened, but somewhat flexible, primary walls. They help support the plant body (as seen in this celery stalk). (c) Sclerenchyma cells have thick, rigid secondary cell walls and die after they differentiate. Illustrated are "stone cells" that give pear fruit its slightly gritty texture.
- #12 FIGURE 42-5 The structure of ground tissue (a) Parenchyma cells are living and serve many functions. They have thin, flexible primary cell walls. These parenchyma cells are used for starch storage in a potato. (b) Collenchyma cells are living and have thickened, but somewhat flexible, primary walls. They help support the plant body (as seen in this celery stalk). (c) Sclerenchyma cells have thick, rigid secondary cell walls and die after they differentiate. Illustrated are "stone cells" that give pear fruit its slightly gritty texture.
- #13 FIGURE 42-5 The structure of ground tissue (a) Parenchyma cells are living and serve many functions. They have thin, flexible primary cell walls. These parenchyma cells are used for starch storage in a potato. (b) Collenchyma cells are living and have thickened, but somewhat flexible, primary walls. They help support the plant body (as seen in this celery stalk). (c) Sclerenchyma cells have thick, rigid secondary cell walls and die after they differentiate. Illustrated are "stone cells" that give pear fruit its slightly gritty texture.
- #30 Figure 35.4 Modified roots
- #32 Figure 35.17 Organization of primary tissues in young stems
- #34 Figure 35.5 Modified stems
- #38 Figure 35.17 Organization of primary tissues in young stems
- #40 Figure 35.7 Modified leaves
- #44 Figure 35.16 The shoot tip
- #45 Figure 35.11 An overview of primary and secondary growth