Biology lecture 3/27/15Vascular plants1. Phylum monilophyta (pterophyta)- Fern life cycle2. Intro to seed bearing plants- What is a seed?Fern sporophytes: sporangia and spore productionFern sporangia/ spore production- Sporangia on underside of leaflets can be numerous or absent- Clusters of sporangia: sori- Sori are variable in position, shape, covering (indusia)Indusia: membranous tissues or sorous - Sori are key taxonomic featuresSori are aggregates of numerous sporangiaLife cycle of a “typical fern”Homosporous “Prothallus”Seed bearing plantsFew generalities of seed-bearing plantsGymnosperms and angiosperms: 2 groups of seed-bearing plantsGymnosperms: naked seedAngiosperm: vessel- Highly reduced (microscopic) gametophytes- All are heterosporousSeed: a mature “ovule”Ovule: 1. Consists of an megasporangium2. Single functional megaspore3. Protective tissue: integumentSolaginella: megaspores released from megasporangium In seed plantsMegaspore divides within megasporangium to form female gametophytesMegasporocute (diploid) → meiosis → megaspore (haploid) → several mitotic divisions → multi-cellular gametophyteAn ovule is distinguished by the microphyla, integument, fuctional megaspore, megasporangium- Rentention of single megaspore in tissues of megasporangium- Development of female gametophyte within megasporangium- Surrounded protective tissue: integument with microphyleSeed-bearing plants produce ovules/seeds and pollenPollen: tiny male gametophyte from microspores in microsporangiumIn microsporangiumMicrosporocyte (diploid) → meiosis → microspores → mitosis → pollen (haploid)Conifer pollen- Prothallial cells- Male gametophyteGenerative cells: spermTube cells: grants access to the eggSequenceOvule → seedQuizlet link:
View Full Document
Unlocking...