BIOL 3427 1st Edition Lecture 7Current LectureI. Secondary growthi. Definition: Increase in thickness or girth of the plant bodyii. Lateral meristemsiii. Vascular cambiumiv. Cork cambiumII. Annuals, Biennials, Perennialsa. Annualsi. Growing season within a calendar yearb. Biennials i. 2 growing seasons (crosses over 2 calendar year)c. Perennialsi. Live for yearsii. Vines, shrubs, treesd. Herbaceousi. A period of dormancy, die back above grounde. Woodyi. Stop growing when unfavorableii. Deciduous1. Drop leaves all at onceiii. Evergreen1. Drop leaves; but not all at onceIII. Vascular Cambiuma. Initialsb. Fusiform initialsi. Vertically oriented; squarish or slightly elongatedc. Ray initialsi. Horizontally oriented; squarish or slightly elongatedd. Secondary vascular tissuese. Axial systemi. Produced by fusiform initialsii. Secondary xylem (inward) and phloem (outward)f. Radial systemi. Produced by ray initialsii. Vascular rays (composed of ray cells)iii. Transport and storage functionsg. Vascular cambiumThese 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.i. Initials also divide anticlinally to increase circumferenceIV. Effects of Secondary growtha. Peridermi. Cork Cambium1. Arises in cortexii. Cork1. Compact: produced to the exterior2. Suberin/wax: laid down during differentiation3. Impermeable to water/ gasesiii. Phelloderm1. Produced to the interior of cork cambium2. Similar to parenchymaV. Tissues present after one year:a. Epidermis remnantsb. Periderm 3 layersc. Cortexd. Primary phloem fibers (other phloem crushed)e. Secondary phloemf. Vascular cambiumg. Secondary xylemi. Differentiated compared to secondary growth of rootsh. Primary xylemi. Pithj. Lenticelsi. Portions of periderm with numerous intercellular spaces1. Gas exchangeVI. Effects of secondary growtha. Barki. All tissues outside vascular cambiumii. Additional cork cambia form1. Arise from parenchyma cells in phloem2. Each deeper than last3. In patches, rings, or intermediate4. Accommodate increasing stem diameterb. Outer barki. Dead tissues= outside inntermost cork cambiumc. Inner barki. Living phloem inside innermost cork cambiumVII. Wood: Secondary xylema. Conifer wood (gymnosperm trees)i. Tracheids, little axial parenchyma (no vessels)ii. Resin ducts-large intercellular spaces lines with parenchyma that secrete resiniii. Protects against fungi, beetles, after wounding, (frost, wind)b. Angiosperm wood:i. Vessels, tracheids, fibers, parenchymaii. Rays often larger than in conifersc. Growth ringsi. Produced by periodic activity of vascular cambiumii. In secondary xylem (and secondary phloem)d. Annual ringsi. If growth ring represents one seasone. False annual ringsi. Change in water availability/environment produces more than one growth ring a yearVIII. Natural selectiona. Some organisms leave more surviving progeny than others due to heritable variationb. Mechanism for evolutionIX. Adaptationa. A structure/physiology/behavior that suits an organism to its environmentX. Species concepta. Biological species concepti. Species: Natural population members that can interbreedii. Difficult to apply to actual data in natureb. Morphological species concepti. Species defined by distinct morphologiesc. Phylogenetic species concepti. Based on reconstructing the evolutionary history of populations and their characteristicsii. Speciation in plants1. Allopatrica. Geographic segregation of plantsd. Sympatric Speciationi. No geographic isolationii. Polyploidy: more than two sets of chromosomes due to nondisjunctioniii. During meiosis/mitosis or no cytokinesis1. Autopolyploidy: within an individual2. Allopolyploidy: a sterile hybrid becomes autopolyploidye. Speciation in plantsi. Role of asexual reproduction1. Sterile hybrids can reproduce asexually (vegetative propogation)2. Others can produce seeds asexually though apomixesf. Chap. 12 Systematics: Study of biological diversity and evolutionary historyi. Taxonomy: Identification, naming, and classification of speciesg. Hierarchical classificationi. International code of botanical nomenclatureii. Binomial Nomenclature (from Carl Lineaus)1. Genus species2. Subspecies or varietyh. Herbaria: where dried plant specimens are stored for referencei. Type specimenXI. Botanical Research Institute of Texasa. Hierarchical classificationi. Kingdom phylum, class, order family, genus species1. Group within any level of categorization called a taxon2. All plant orders end in -ales3. All plant families end in aceaeii. Outward similarities1. Traditional classification based on opinion, not detailed enoughiii. Phylogenetic analysis (cladistics)1. Based on evolutionary relationships and analysis of primitive and advanced features2. Molecular systematics allows genetic comparison of organisms3. Provides more characteristics for phylogenetic analysisXII. Current classificationa. Three domains of lifei. Bacteriaii. Eukaryaiii. Archaeb. Eukaryai. Fungiii. Protista iii. Plantaeiv. AnimaliaXIII. Kingdom fungia. Unicellular and filamentous multicellularb. Lack plastids and photosynthesisc. Absorb nutrients from living or dead organismsd. Chitin cell wallse. Usually asexual and sexual reproductionf. Relationships with plantsi. Pathogensii. Mycorrhizaeiii. Lichens (Fungus and green algae/cyanobacteria)XIV. Kingdom Animaliaa. Multicellular often motileb. No cell walls, or plastidsc. Most use ingestion to obtain energyd. Usually sexual reproductione. Relationships with plantsi. Extensive human useii. Herbivoresiii. Use for housing protectionXV. Kingdom Protistaa. Unicellular colonial simple multicellularb. Protazoa; algae water molds, slime moldsc. Autotrophs, heterotrophs, myxotrophsd. Reproduction by cell division and sexual reproductionXVI. Kingdom Plantaea. Ancestors: specialized green algaeb. Multicellularc. Nutrition through photosynthesisi. A few heterotrophsd. Primarily sexual reproduction (Alternation of generations)XVII. Life Cycles and Diploidya. Types of meiosisi. Zygotic: zygote is the only 2n condition; organism usually nii. Fungi; some algaeiii. Gametic: organism usually 2n only gametes niv. Animals; some protists, some algaev. Sporic: Meiosis produces n sporesvi. Multicellular 2n and n conditionsvii. Alternation of generationsviii. Plants some algaeXVIII. Alternation of generationsa. Gametophytei. N; produces gametesii. Haploidb. Sporophytei. 2n produces sporesii. Diploidc. Isomorphic versus