Biology reading for 3/4/15 pages 178-180Mosses and other nonvascular plants have liveCycles dominated by gametophytesThree phyla of small herbaceous plants that represent bryophytes: liverworts, hornworts, and mossesBryophytes: nonvascular plantsLiverworts: small herbaceous, nonvascular plant that is a member of the phylum HepatophytaMosses: a small, herbaceous, nonvascular plant that is a member of the phylum BryophytaHornworts: small herbaceous, nonvascular plant that is a member of the phylum AnthocerophytaWort is anglo-saxon for “herb”Bryophyte GametophytesBryophyte phyla are larger and longer-living than sporophytesBryophytes germinate in favorable environments and grow into gametophytesProtonema: green, branched, one-cell thick filaments. Has a large surface area that enhances absorption of water and mineralsGametophore: gamete-producing structure. Makes up the body of a moss gametophyte with a protonema.Rhizoids: long tubular single cells (in liverworts or hornworts) or filaments of cells (in mosses) that anchor the gametophytesRhizoids are not composed of tissues.Life cycle of a moss: 1. Spores develop into threadlike protonemata → (haploid) 2. The haploid proteonemata produce “buds” that divide by mitosis and grow into gametophores →(haploid) 3. Sperm must swim through a film of moisture to reach the egg →(haploid) → fertilization within archegonium →(diploid) 4. The zygote develops into a sporophyte embryo →(diploid) 5. The sporophyte grows a long stalk (seta) that emerges from the archegonium →(diploid) 6. Attached by its foot, the sporophyte remains nutritionally dependant on the gametophyte →(diploid) 7. Meiosis occurs and haploid spores develop in the capsule. When the capsule is mature, the sporesare released →(haploid) step 1.Bryophyte diversityLiverworts (phylum Hapatophyta)Liver-shaped gametophytes. Some are described as “thalloid” because of flattened gametophytes.Hornworts (phylum Anthocerophyta)Long-tapered shaped sporophyte. Lacks a seta and consists only of a sporangium.Mosses (phylum Brophyta)Gametophytes range in height less than 1mm. Consists mainly of gametophytes. Blades of the leaves are usually one cell thick.Quizlet link: