Ch1: The Science of Plant SystematicsCh1: The Science of Plant Systematics- General plant chs.- What is plant systematics?- How are phylogenies determined?- What is the value of systematics?.I. Introduction A. What is a plant? (pp. 4-5)“green algae” & “land plants”, or the ChlorobiontaB. General plant chs. 1. chlorophylls a & b, carotenoids2. store food as starch within chloroplasts(endosymbiosis)C. Chs. of land plants (Kingdom Plantae) (pp. 53-55)1. sporic meiosis2. embryos 3. multicellular4. alternation of heteromorphic generations5. largely terrestrial6. cuticles7. largely terrestrialD. Major plant groups1. nonvascular (bryophytes):mosses, liverworts, hornworts2. vascular (or tracheophytes):a. seedless vascular:--seed producers:b. gymnosperms:c. angiosperms:E. What is plant systematics? (p. 9)1. = science of plant diversity & phylogenetic relationshipsphylogeny = ancestral history or 2. major goalsa. discoveryb. description (characters)c. identification = recognize structural features & assign plant to a known, named group of plants1d. nomenclature = apply names (Latin, or scientific) to taxa according to International Code of Botanical Nomenclature e. classification = placement of taxa into groups, organizedscheme of relationshipsUsually hierarchicaltaxon (taxa, pl.) = group of organisms of any Classifications have 8 major taxonomic ranks3. two major approaches to classification (p. 13)a. theory-grounded (phylogenetic)-- hypotheses about relationshipsb. theory-neutral (phenetic)-- doesn’t claim to convey infoabout evolutionary relationshipsII. Plant systematics vs. taxonomyA. taxonomy = science of discovering, identifying, naming, & 1. Candolle (1813)2. classificationB. Terms often used as synonymsC. Taxonomy is subset of systematics? See p. 9.III. Constructing phylogeniesA. Evolution basedB. Today attempts to construct monophyletic groups (taxa)monophyletic group = all descendants of Can be represented on evolutionary diagram, or cladogram--removed from diagram by a single cut below a node. Fig. 1.9 (p. 14) C. May construct evolutionary diagrams; see p. 14D. Relationships assumed based on structural/molecular evidence(e.g., morphology, DNA)E. Actual lineages are unknown!-- hypothesesF. Dynamic.IV. Value of plant systematics?A. Framework for communicationB. Organize/summarize infoC. Prediction – search for related species/chs.E. Explanations for adaptations, structural changesComparative