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 • ____________________ Ø photosynthesis Ø storage Ø support • ____________________ Ø conduction Ø support • ___________________ Ø Covering Ground Tissue System • ___________ Tissue • Collenchyma Tissue • Sclerenchyma Tissue Parenchyma Tissue • Made up of Parenchyma Cells • __________ 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) • _________ or _________ • Function – Support Vascular Tissue System • Xylem – H2O – ___________ – Vessel Elements • Phloem - Food – Sieve-tube Members – __________ 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 • _____________ – alive at maturity – lack nucleus – Sieve plates - on end to transport food • _____________ – 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 • ___________ – – replaces epidermis in woody plants – protection • ____________ – Tap Root – Lateral Roots • ____________ – Stems • Nodes (leaves are attached) • Internodes – Leaves • blades • petioles – Buds • Terminal (apical) Plant • Axillary Systems Plant Growth • ______________ Tissue – generates cells for new growth (like stem cells in animals) • apical meristems • lateral meristems Apical Meristems • increases length called primary growth – ___________ - gives rise to dermal tissue – ________________- gives rise to ground tissue – _____________ - gives rise to vascular tissue Lateral Meristems • increases girth called secondary growth – __________________- produces secondary xylem and secondary phloem – ______________- 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 – ____________ - one large root with smaller lateral roots (dicots) – ____________- threadlike roots (monocots) Root Structure • Four Regions – _________– protection, also secrete polysaccharide slime to lubricate – Region of ___________- new cells – Region of __________ - cells get longer – Region of _________ - cells begin to specialize Root Tissue • Protoderm - gives rise to the epidermis • Ground Meristem – Cortex (external to vascular tissue) • Procambium - gives rise to the _______ (the vascular tissue of a root or stem) – xylem and phloem – may include pith (parenchyma cells surrounded by vascular tissue) Dicot Root vs. Monocot 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 ____________ – stele (vascular tissue) divided into strands in stems and leaves Sclerenchyma cells Phloem Xylem Dicot Stem Vs. Monocot (35.16) 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! ___________ (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 • __________ - 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) • _____________ - cactus pads Leaf Structure Leaves • Epidermis – __________ - openings on underside of leaf – Guard Cells - surround stomata – Cuticle - waxy coating excreted by epidermis • Mesophyll - middle of leaf – ___________ - photosynthesis – Spongy layer - gas exchange Modified Leaves • ___________- attachment • Bracts –modified leaves that surround a group of flowers • Spines - protection • Storage Leaves - succulents .

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