Lecture 3: Plant anatomy and physiologyToday…Announcements…From smallest to largest plantsWhat is plant anatomy?“Structure correlates to function”Slide 7Plant Anatomy: CellsPlant Tissues Types1. Dermal tissue2. Vascular tissueXylemXylem cellsPhloemPhloem: transports sugars3. Ground tissuePlant OrgansFunctions of plant organs:ROOTSAnatomy of a rootRoot EpidermisRoot Hairs: water and mineral absorptionRoot CortexRoot Ground tissueRoot Cortex: EndodermisRoot cortex: Casparian stripSTEMSStem anatomyTypes of StemsTypes of stemsTissues of stemsStem Vascular tissueVascular cambiumVascular tissue: TreesGirdling: cutting around a treeVascular tissue forms rings in treesHistory of the tree: annual ringsGround tissue: Cortex & pithLEAVES:Leaf AnatomyLeaf epidermisSlide 42Leaf vascular tissueLeaf MesophyllPlant water transportWater transport in plants:Transpiration-cohesion Theory for water transport in the xylemWater transport (cont.)Sugar translocationPressure flow in phloemPlant Hormones1. AUXINS2. Gibberellins5. ETHYLENE“One rotten apple spoils the barrel”Avocado ripening…Lecture 3: Plant anatomy and Lecture 3: Plant anatomy and physiologyphysiologybyEdgar Moctezuma, Ph.D.Today…•Announcements•Plant Anatomy–Cells–Tissues–Organs•Plant Physiology–Water & sugar transport–Plant hormonesAnnouncements…•Labs start this week – get your lab manual.•BSCI 125 students: if you have the following sections:–1109, 1110 Tues. 3:30-5:30 or,–1113, 1114 Wed. 12-2 or,–1115, 1116 Wed. 3-5 or–1123, 1124 Thurs. 3:30-5:30, and you can switch to an open section (Monday or Wed. 9:00-11:00), please try to do so. Thanks!•Taking care of your plant:–Do not overwater it! Water only when soil is dry to the touch.–Place near a sunny window.From smallest to largest plantsWhat is plant anatomy?•ANATOMY: study of the structure of organisms… looking at cells, tissues•(Morphology: Study of form)What is plant physiology?•PHYSIOLOGY: study of the function of cells, tissues, organs of living things; and the physics/chemistry of these functions…“Structure correlates to function”Always keep in mind that in plant anatomy, morphology & physiology…•How can water move from the ground all the wayto the topof a 100 mtall redwoodtree?Plant Anatomy: Cells•Plant cells are basic building blocks•Can specialize in form and function•By working together, forming tissues, they can support each other and survive •Levels of organizationatoms > molecules > cells > tissues > organs > whole plant > pop.Plant Tissues TypesAll plant organs (roots, stems, leaves) are composed of the same tissue types.There are three types of tissue:•1. Dermal – outermost layer•2. Vascular – conducting tissue, transport•3. Ground – bulk of inner layers1. Dermal tissue•Epidermis is the outermost layer of cells•Like the “skin” of animals•In stems and leaves, epidermis has cuticle, a waxy layer that prevents water loss.•Some have trichomes, hairs.•Root epidermis has root hairs, for water and nutrient absorption2. Vascular tissue•Transports water and organic materials (sugars) throughout the plant •Xylem – transports water and dissolved ions from the root to the stem and leaves.• Phloem – carries dissolved sugars from leaves to rest of the plantXylem•Transports water and dissolved minerals•Tracheids: long, thin tube like structures without perforations at the ends•Vessel elements: short, wide tubes perforated at the ends (together form a pipe, called vessel).•Both cells have pits (thin sections) on the walls Tracheids Vessel elementsXylem cells•Xylem cells are dead!•They are hollow cellsand consist only ofcell wallPhloem•Cells that transport organic materials (sugars)•Phloem cells are ALIVE! (unlike xylem)•However, they lack nucleus and organellesPhloem: transports sugars•Phloem composed of cells called sieve tube members (STM)•Companion cells join sieve tube members, are related, and help to load materials into STM•End walls of STM have large pores called sieve platesSieve tube memberCompanion cellsSieve plates3. Ground tissue•Makes up the bulk of plant organs. •Functions: Metabolism, storage and support.Root Stem LeafPlant Organs Organs: tissues that act together to serve a specific function•Roots•Stems•LeavesDermalVascularGroundDermalVascularGroundDermalVascularGroundFunctions of plant organs:•ROOTS: Anchorage, water/nutrient absorption from soil, storage, water/nutrient transport•STEMS: Support, water/nutrient transport•LEAVES: Photosynthesis (food production)ROOTS•ROOTS “the hidden half”•Functions of roots:•Ancorage•Absorption of water & dissolved minerals•Storage (surplus sugars, starch)•Conduction water/nutrientsAnatomy of a rootepidermiscortexvascularRoot Epidermis•Outermost, single layer of cells that:–Protects (from diseases)–Absorbs water and nutrients•ROOT HAIRS: tubular extensions of epidermal cells.•Increase surface area of root,for better water/nutrient absorptionRoot Hairs: water and mineral absorptionRoot hairs increase surfacearea for betterabsorptionRoot Cortex•Stores starch, sugars and other substancesRoot Ground tissue•In roots, ground tissue (a.k.a. cortex) provides support, andoften stores sugars and starch (for example: yams, sweet potato, etc.)Hey! I yam what I yam, man!You’re not a yam, you’re a sweetpotato!cortexRoot Cortex: Endodermis•Endodermis: the innermost layer of the cortexRoot cortex: Casparian strip•The Casparian strip is a water-impermeable strip of waxy material found in the endodermis (innermost layer of the cortex). •The Casparian strip helps to control the uptake of minerals into the xylem: they have to go through the cytoplasm of the cell!STEMS•Above-ground organs (usually)•Support leaves and fruits•Conduct water and sugarsthroughout plant (xylem and phloem)Stem anatomy•Dermal, ground and vascular tissues…pithcortexepidermisVascularbundlesTypes of StemsMonocot stem Dicot stem RootTypes of stems•Herbaceous vs. Woody stemsTissues of stems•Epidermis (Dermal tissue type)•Provides protection•Has cuticle (wax) prevents water loss•Trichomes (hairs) for protection, to release scents, oils, etc.Stem Vascular tissue•Vascular bundles – composed of both xylem and phloem•Xylem–Conducts water–Support•Phloem–Conducts food–SupportVascularcambiumVascular