CHAPTER 35

• Plants have three types of tissues: dermal, vascular, and ground
• Dermal tissue serves as a protective outer covering for plants
• Vascular tissue facilitates the transport of materials through the plant and provides mechanical support
• Ground tissue includes cells specialized for storage, photosynthesis, support, and short-distance transport
• Plant organs are composed of tissues, which are composed of cells
• A cell is the fundamental unit of life
• A tissue is a group of cells consisting of one or more cell types that together perform a specialized function
• An organ consists of several types of tissues that together carry out particular functions
• The three basic organs of plants are leaves, stem, and roots
• Leaves provide surface area for photosynthesis
• Stems provide support and elevate the plant
• Roots provide anchorage and absorption of water and minerals in the soil
• Roots, stems, and leaves are composed of three tissue types: dermal, vascular, and ground tissues
• Dermal tissue serves as a protective outer coating
• Common types of plant cells include parenchyma, collenchyma, sclerenchyma, water-conducting cells of the xylem, and sugar-conducting cells of the phloem
• Parenchyma cells perform most of the metabolic functions and retain the ability to divide and differentiate
• Collenchyma cells help support young parts of the plant shoot and provide flexible support without restraining growth
• Sclerenchyma cells have rigid secondary cell walls containing lignin for support
• Water-conducting cells of the xylem have lignified secondary cell walls for plant support
• Sugar-conducting cells of the phloem transport sugars from leaves to actively growing parts of the plant or storage structures
• Primary growth is made possible by apical meristems at the tips of shoots and roots
• Apical meristem cells are undifferentiated and give rise to different tissues needed by the plant
• Secondary growth, which occurs in thickness, is facilitated by the lateral meristem
• Vascular cambium produces secondary xylem and phloem, while cork cambium adds layers of cork including the periderm as the plant matures
• Vascular cambium adds xylem and phloem to the stem
• Vascular cambium alternates between making xylem and phloem to maintain itself
• Main reason why tree trunks thicken with age?


  vascular cambium
• Cork cambiums work at the same time as the vascular cambium
• Secondary growth adds cork that protects and waterproofs stems and roots
• Vascular cambium makes xylem and phloem by dividing its cells repeatedly
• More divisions produce xylem than phloem
• Three zones of growth in roots: zones of cell division, elongation, and differentiation/maturation
• Root cap protects the apical meristem and produces polysaccharide slime
• Arrangement of vascular tissues in eudicots and monocots
• Leaf anatomy: cuticle, stomata pores, epidermis, mesophyll (palisade and spongy)
• Secondary growth of a woody stem: vascular cambium produces secondary xylem and phloem, cork cambium produces cork cells
• Orientation of plant cell expansion along the main axis
• Distinct rings in stem for dendrochronology, hardwood vs sapwood, periderm formation
• Phase change in plants from juvenile to adult stages
• Genes and pattern formation in flower development: transition to flowering, ABC hypothesis for floral organ formation