BIOL 225 Lecture 2: Lecture 2, week 1 BIOL 225 notes
6 Feb 2017
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Objectives: shared traits btw land plants and charophytes, key innovations of land plants (derived traits, key innovations within clades of plant kingdom. 1rst 3 billion years of earth"s history, terrestrial surface was lifeless. Since colonizing land, plants have diversified into roughly 290,000 living species. Green algae, called charophytes are the closest relatives of land plants. Key innovations of land plants: alternation of generations and multicellular, dependent embryos, walled spores produced in sporangia (produce spores, multicellular gametangia (produce gametes, apical meristems. Sporangium disperse spores (haploid) , spores are protected by sporopollenin > young gametophyte > mature gametophyte > antheridium / archegonium. Land plants subdivided into 4 clades: non-vascular plants, seedless vascular plants, vascular seed plants, fruit-producing vascular seed plants. Giant lycophytes trees thrived for millions of years in moist swamps. Decaying plants of these carboniferous forests eventually became coal. Seeds changed the course of plant evolution. Seed consists of an embryo and nutrients surrounded by protective coat.
