BIOL 420 1st Edition Lecture 12Angiosperms: Roots and StemsText Reference:Chapter 24, The Root: Structure and DevelopmentChapter 25, The Shoot: Primary Structure and DevelopmentRoots – FunctionsCan grow around and can get woodier as it grows and kills the tree they are growing on.- Anchorage: anchoring the plant- Absorption: absorbing nutrients – water and minerals- Storage: nutrients (sweet potato – starch)- Conduction: involved in transporting food substances, in the 2nd year, it is going to be broken down and the phloem is going to be used up instead of down and around.- Reproduction –clonal regeneration. Asexual produced, as a normal option. If there is damage to the parent plant, then the roots can regenerate the entire plant- Synthesis and secretionRoot Systems- Primary root: most dicots send down the radical becomes the primary root and forms a cap root that goes in deep into the soil to search water.- Taproot: can grow to grab water and to keep the roots close together so once it rains it can capture the water more likely.- Lateral roots: to increase surface space, grows root hairs which have extremely thin wallso Fibrous roots: lateral roots give rise to this. - Adventitious roots: the stem-borne roots- Paricima cells: the root cap, the mesophyll also contains these cells, the go to building block for plant anatomy. The root cap is used to protect as it grows downwards.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Examples of root form and growthDepth of Root System- Boscia albitrunca – 68 meter deptho Plants that grow in the dessert- Prosopsis – 53 meters deptho Mesquite genus; also grows in desserts- Tamarix and Acacia – 30 meterso Juviniles and can grow into an adult plant. Acacia – in the bean lugene family- Medicago (Alfalfa) – 6 meters o Lugene family (bean) Surface Area Covered-Secale (rye) – 4 months, 639 square metersBalance Between Roots and Shoots- Ratio between roots and shootso Underwater can increase the root:shoot ratio; anytime you move plants it is important to not damage the root system.Root Structure – External anatomy- Rootcap: can consists of living cells, generic permical cells. Protect the tissue above them – which is really important which pushes the roots through the soil.- Columella – gravitropism and hydrotropism - the ones that can sense water and sensitive to gravity so it can grow down- Mucilage sheath: gives lubrication to help move through the soil easier/faster- Root hairs: to increase surface area, growing from the epidermis- Lateral roots: new roots that are forming from the tissue pericycleRoot Structure – longitudinal- Rootcap- Apical meristem (Zone of cell division): results in growth; dermal cell and ground that’sgoing to form the cortex. Where mitosis is occurring- Zone of cell elongation: when plant cells divide, they tend to be a little. square. Many plant cells stretch into becoming a more rectangular shape. Results in grown. Pretty muchthat’s the point where primary growth stops; anything before that it becomes different cells- Zone of maturation (differentiation): cells are maturing; they are taking on specific functions.Root Structure – cross section (dicot)- Epidermis: single layer, design to protect because it doesn’t have much of a cell wall. Pretty thin, root tips vulnerable to insects, mammals, etc.- Cortex: g round tissue, the cells have a little bit of space between them. Acts like a sponge. Water and minerals can flow easily into the cortex in the root system. Pretty thick;- Endodermis – Casparian strips: have between them these strips and it’s part of the cell wall, addition to the cellulose there are a lot of proteins absorb in the strip, this strip makes it preamble to water. Can make water and minerals flow freely. To a large extent can control what can be flowed into the xylem for further transport in the plant body- Pericycle: are the cells that differentiate into the lateral roots (which grows through the endodermis which proceeds to grow into the cycle.)- Phloem: located around the xylem. Bringing glucose and nutrients down- Xylem: dead center in the root, like a cross. Conducts water upRoot Structure – comparison of monocots and dicots- Ranunculus (buttercup) – dicot- Zea mays (corn) – monocotAbsorptive Function of Roots- Process – transport of water and minerals to xylem- Role of mycorhizal fungi: allow trees to reach the size they can reach, not the roots because it is not efficient enough to receive water. Parastitic, growing into the root to steal the nutrients, and then it makes it easier for the plant to receive water.Formation of lateral roots- Pericycle- Root primordiumModified Roots- Prop roots: can be found on good many plants, if the plants are tall and thin or can be knocked down easily (like corn). Grow in wet areas and need the extra support. Grow from the prop/side of the plant, once they touch the soil the later root starts to grow and function as normal roots.- Stilt roots: are produced from the stems and branches of many tropical trees- Pneumatophores: extreme exaggerated prop roots. This would help it from not being blown down, etc. extra measure of strength and stability. Growing in swampy habitats- Epiphytic roots – orchids - grow on the body of other trees, not parasitic. Root systems of majority does not grow into the tree, instead it is- Storage rootsThe Shoot: Primary Structure and DevelopmentText Reference: Chapter 25The shoot - stem and leaves- Leaves-Stem-Node-Internode: space between the nodes- Bud: embryonic leaf or flower, lateral branch – produces varies from species. - Apical meristem (stem cells): cells that can differentiate into something-Leaf primordium: going to form vascular issue-Bud primordiu: grows into lateral shoots-Ground meristem: ground tissue - mesophyll-Leaf trace: the vascular tissue leaves the states and enters the leaf (the veins)- Sclerenchyma: can produce protein that can get hard and give support where they are found, also gives tissue protectionSecondary growth in the stem – basswood-Tilia americana - basswood- Vascular cambium: produces secondary xylem and phloem; each year its going to produce a ring.- Primary phloem- Secondary phloem- Primary xylem- Secondary xylem- Bark- LenticelMonocot stem - Zea mays (corn)- Epidermis- Ground tissue- Vascular bundles- Xylemo Tracheidso Vessels-