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- 1. March 28, 2005 Plant Tissues Chapter 26 Jin Hoe Huh
- 2. Angiosperms – floweringplants • The angiosperms are seed-bearing vascular plants • In terms of distribution and diversity, they are the most successful plants on Earth • The structure and function of this plant group help explain its success
- 3. Flowering Plant Life Double fertilization Diploid Meiosis Meiosis Cycle Haploid Mitosis without microspores pollination cytoplasmic division Two sperms enter ovule Female gametophyte
- 4. Plant Life Histories •Annuals complete life cycle in one growing season • Biennials live for two seasons; flowers form in second season • Perennials grow and produce seeds year after year
- 5. Shoot and Root Systems Shootsystem - produces sugars by Shoot photosynthesis System - carries out reproduction Root system - anchors the plant - penetrates the soil and Root absorbs water and minerals System - stores food
- 6. Shoot and root systemsare interdependent water & sugar minerals SHOOT SYSTEM ROOT SYSTEM
- 7. Plant Tissue Systems EPIDERMIS • Ground tissue VASCULAR TISSUES system • Vascular tissue GROUND TISSUES system SHOOT SYSTEM • Dermal tissue ROOT SYSTEM system
- 8. Meristems – WhereTissues Originate • Regions where cell divisions produce plant growth • Apical meristems – Lengthen stems and roots – Responsible for primary growth • Lateral meristems – Increase width of stems – Responsible for secondary growth
- 9. Apical Meristems Lengthen shootsand roots: activity at meristems SAM and RAM Cells that form at apical new cells elongate meristems: and start to differentiate protoderm epidermis into primary tissues ground meristem ground tissues procambium primary vascular tissues
- 10. Lateral Meristems Increases girthof older roots and stems Cylindrical arrays of cells vascular cambium secondary vascular tissues periderm cork cambium thickening
- 11. Simple Tissues Made upof only one type of cell Parenchyma Collenchyma Sclerenchyma
- 12. Morphology of threesimple tissue types parenchyma collenchyma sclerenchyma
- 13. Parenchyma: A SimpleTissue • Comprises most of a plant’s soft primary growth • Cells are pliable, thin walled, many sided • Cells remain alive at maturity and retain capacity to divide • Mesophyll is a type of parenchyma that contains chloroplasts
- 14. Collenchyma: A SimpleTissue • Specialized for support for primary tissues • Cells are elongated, with walls (especially corners) thickened with pectin • Makes stems strong but pliable • Cells are alive at maturity
- 15. Sclerenchyma: A SimpleTissue • Supports mature plant parts • Protects many seeds • Cells have thick, lignified walls and are dead at maturity • Two types: – Fibers: Long, tapered cells – Sclereids: Stubbier cells
- 16. Complex Tissues Composed ofa mix of cell types Xylem Phloem Epidermis
- 17. Xylem • Conducts water and dissolved minerals • Conducting cells are dead and hollow at maturity vessel member tracheids
- 18. Phloem: A Complex Vascular Tissue sieve plate • Transports sugars • Main conducting cells are sieve- tube members sieve-tube • Companion cells member companion assist in the cell loading of sugars
- 19. Epidermis: A Complex Plant Tissue - Covers and protects plant surfaces - Secretes a waxy, waterproof cuticle - In plants with secondary growth, periderm replaces epidermis
- 20. Monocots and Dicots– same tissues, different features 1 cotyledon 2 cotyledons 3 floral 4 or 5 floral parts parts Netlike veins Parallel veins 1 pore 3 pores Vascular Vascular bundles bundles in ring dispersed
- 21. shoot apical meristem Shoot protoderm procambrium ground meristem Development cortex procambrium pith primary xylem primary phloem
- 22. Bud = undevelopedshoot of meristematic tissue Leaves Internode Axillary bud at node Longitudinal section of terminal bud
- 23. Roots also havemeristems
- 24. Internal Structure ofa Dicot Stem - Outermost layer is epidermis - Cortex lies beneath epidermis - Ring of vascular bundles separates the cortex from the pith - The pith lies in the center of the stem
- 25. Internal Structure • The vascular bundles of a are distributed Monocot throughout the ground tissue Stem • No division of ground tissue into cortex and pith
- 26. Dicots Monocots Ground tissue system Dermal tissue system Vascular tissue system Dicots and Monocots have different stem and root anatomies
- 27. Leaf Gross Structure DICOT MONOCOT petiole axillary bud blade node sheath blade node
- 28. 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 – Arrange so they don’t shade one another
- 29. Leaf Structure UPPER cuticle EPIDERMIS PALISADE MESOPHYLL xylem SPONGY MESOPHYLL phloem LOWER EPIDERMIS O2 CO2 one stoma
- 30. Mesophyll: Photosynthetic Tissue • Atype of parenchyma tissue • Cells have chloroplasts • Two layers in dicots – Palisade mesophyll – Spongy mesophyll
- 31. Collenchyma Parenchyma
- 32. Leaf Veins: VascularBundles • Xylem and phloem – often strengthened with fibers • In dicots, veins are netlike • In monocots, they are parallel
- 33.
- 34. Root Structure • Rootcap covers tip • Apical meristem produces the cap • Cell divisions at the apical meristem cause the root to lengthen • Farther up, cells differentiate and mature root apical root cap meristem
- 35. Internal Structure ofa Root • Outermost layer is epidermis • Root cortex is beneath the epidermis • Endodermis, then pericycle surround the vascular cylinder • In some plants, there is a central pith
- 36. epidermis endodermis cortex pericycle root hair phloem xylem
- 37. Root Hairs andLateral Roots new • Both increase the surface lateral root area of a root system • 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
- 38. Secondary Growth • Occursin perennials • A ring of vascular cambium produces secondary xylem and phloem • Wood is the accumulation of these secondary tissues, especially xylem
- 39.
- 40. Woody Stem periderm (consistsof secondary HEARTWOOD SAPWOOD cork, cork cambium, phloem and secondary cortex) BARK vascular cambium
- 41. Annual Rings • Concentricrings of secondary xylem • Alternating bands of early and late wood • Early wood – Xylem cells with large diameter, thin walls • Late wood – Xylem cells with smaller diameter, thicker walls
- 42. Types of Wood •Hardwood (oak, hickory) – Dicot wood – Xylem composed of vessels, tracheids, and fibers • Softwood (pine, redwood) – Gymnosperm wood – Xylem composed mostly of tracheids – Grows more quickly