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 • ____________________ photosynthesis storage support Vascular Tissue System • ____________________ conduction support Dermal Tissue System • ___________________ 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 Companion Cell (on the side) members • Sieve-tube _____________ – alive at maturity – lack nucleus – Sieve plates on end to transport food Companion Cells • _____________ – alive at maturity – helps control sieve-tube 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 Plant Systems • Terminal (apical) • Axillary 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 Cell Division –Region of ___________new cells Elongation –Region of __________ - cells get longer Maturation - cells –Region of _________ 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 rise to lateral roots “Pith” – central core of parenchyma cells surrounded by xylem and phloem Modified Roots • Food Storage – carrots, sweet potatoes, yams • Water Storage – pumpkin family • Propagative Roots – cherries, pears • Pnematophores – mangroves • Aerial Roots – orchids • Buttress Roots – tropical trees • Haustoria – 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 • Pith • Primary Xylem • Secondary Xylem (wood) • Vascular Cambium Periderm Secondary Growth of a Stem (Inside to Outside) • Secondary Phloem • Primary Phloem • Cortex • Phelloderm • Cork Cambium • 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