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Plant Structure and Growth

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Plant Structure and Growth Plant Structure And Growth The Plant Body is Composed of Cells and Tissues • Tissue systems (Like Organs) – made up of tissues • Made up of cells Plant Tissue Systems • ____________________Ground Tissue System Ø photosynthesis Ø storage Ø support • ____________________Vascular Tissue System Ø conduction Ø support • ___________________Dermal Tissue System Ø Covering Ground Tissue System • ___________Parenchyma Tissue • Collenchyma Tissue • Sclerenchyma Tissue Parenchyma Tissue • Made up of Parenchyma Cells • __________Living Cells • Primary Walls • Functions – photosynthesis – storage Collenchyma Tissue • Made up of Collenchyma Cells • Living Cells • Primary Walls are thickened • Function – _Support_____ Sclerenchyma Tissue • Made up of Sclerenchyma Cells • Usually Dead • Primary Walls and secondary walls that are thickened (lignin) • _________Fibers or _________Sclerids • Function – Support Vascular Tissue System • Xylem – H2O – ___________Tracheids – Vessel Elements • Phloem - Food – Sieve-tube Members – __________Companion Cells Xylem • Tracheids – dead at maturity – pits - water moves through pits from cell to cell • Vessel Elements – dead at maturity – perforations - water moves directly from cell to cell Phloem Sieve-tube member • Sieve-tube_____________ members – alive at maturity – lack nucleus – Sieve plates - on end to transport food • _____________Companion Cells – alive at maturity – helps control Companion Cell (on sieve-tube the side) member cell Dermal Tissue System • Epidermis – Single layer, tightly packed cells – Complex Tissue – Does different things in different areas (roots vs. leaves) – usually transparent – secretes cuticle • ___________Periderm – – replaces epidermis in woody plants – protection • ____________Root System – Tap Root – Lateral Roots • ____________Shoot System – Stems • Nodes (leaves are attached) • Internodes – Leaves • blades • petioles – Buds • Terminal (apical) Plant • Axillary Systems Plant Growth • ______________Meristematic Tissue – generates cells for new growth (like stem cells in animals) • apical meristems • lateral meristems Apical Meristems • increases length called primary growth – ___________Protoderm - gives rise to dermal tissue – ________________Ground Meristem - gives rise to ground tissue – _____________Procambium - gives rise to vascular tissue Lateral Meristems • increases girth called secondary growth – __________________Vascular Cambium - produces secondary xylem and secondary phloem – ______________Cork Cambium - produces cork (outer most layer of bark) Pine Tree w/ 8 Cotyledons! The Root System • Functions – anchor plant – absorb minerals, water and nutrients – store food • Systems – ____________Tap roots - one large root with smaller lateral roots (dicots) – ____________Fibrous roots - threadlike roots (monocots) Root Structure • Four Regions – _________Root Cap – protection, also secrete polysaccharide slime to lubricate – Region of ___________Cell Division - new cells – Region of __________Elongation - cells get longer – Region of _________Maturation - cells begin to specialize Root Tissue • Protoderm - gives rise to the epidermis • Ground Meristem – Cortex (external to vascular tissue) • Procambium - gives rise to the _______Stele (the vascular tissue of a root or stem) – xylem and phloem – may include pith (parenchyma cells surrounded by vascular tissue) Dicot Root vs. Monocot Xylem (larger, in red) Endodermis Phloem (smaller, greenish) Pericycle – one layer IN from endoderm, gives “Pith” – central core of rise to lateral roots parenchyma cells surrounded by xylem and phloem Modified Roots • Food Storage • Pnematophores – carrots, sweet – mangroves potatoes, yams • Aerial Roots • Water Storage – orchids – pumpkin family • Buttress Roots • Propagative – tropical trees Roots • Haustoria – cherries, pears – dodder Shoot System The Shoot System • Made up of Stems, Leaves, Flowers, Fruits – Stems - support, conduction, growth – Leaves - photosynthesis – Flowers - pollination – Fruits - seed protection, dispersal Stems (Primary Growth) • Protoderm - gives rise to the epidermis • Procambium - gives rise to the stele – xylem and phloem in vascular bundles • dicots - found in ring • monocots - scattered throughout – includes “pith” in dicots • Ground Meristem – Cortex ____________Vascular Bundle – stele (vascular tissue) divided into strands in stems and leaves Sclerenchyma cells Phloem Xylem Dicot Stem Vs. Monocot (35.16) Vascular Bundle Ground Tissue (Pith) (Cortex) How can you tell root from stem? Stems (Secondary Growth) • Occurs to increase girth (thickness) – Vascular Cambium • produces secondary xylem and secondary phloem – Cork Cambium • produces cork and phelloderm (thin layer of parenchyma cells) • together these structures are called periderm (Cork Cambium, cork, phelloderm) Secondary Growth Derivative Vascular cambium Secondary Growth of a Stem Secondary Growth of a Stem (Inside to Outside) • Pith • Secondary Phloem • Primary Xylem • Primary Phloem • Secondary Xylem • Cortex (wood) • Phelloderm • Vascular • Cork Cambium Cambium Periderm • Cork (outer layer of bark) Older, inner layers of 2° Xylem – no longer transport water Younger, outer layers of 2° Xylem still function in transport All tissue outside vascular cambium Missing cortex and phelloderm! ___________Springwood (Early) growth occurs more quickly. Cells are large and thin walled and have less strength. Summerwood (Late) growth occurs more slowly. Cells are thicker, more dense, and stronger. Secondary Growth of a Stem Modified Stems • __________Stolons - horizontal stems above the ground (strawberries) • Rhizomes - horizontal stems below the ground (Irises) • Tubers - swollen areas of rhizomes or stolons (Potatoes) • Bulbs & Corms - vertical shoots under ground (onions, garlic w/ mod storage leaves) • _____________Cladophylls - cactus pads Leaf Structure Leaves • Epidermis – __________Stomata - openings on underside of leaf – Guard Cells - surround stomata – Cuticle - waxy coating excreted by epidermis • Mesophyll - middle of leaf – ___________Palisade Layer - photosynthesis – Spongy layer - gas exchange Modified Leaves • ___________Tendrils - attachment • Bracts –modified leaves that surround a group of flowers • Spines - protection • Storage Leaves - succulents .
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