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UT Arlington BIOL BIOL 3427 - Ch 22 Seedless Plants

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22.1 Mosses22.2 Liverworts and Hornworts22.3 Seedless Vascular Plants22.1 MossesChapter 22: Seedless PlantsObjectives22.1 Mosses- Identify some characteristics of mosses.- Describe the life cycle of mosses22.2 Liverworts and Hornworts- Discuss the characteristics of liverworts and hornworts- Compare and contrast liverworts, hornworts and mosses22.3 Seedless Vascular Plants- Describe the characteristics of seedless vascular plants- Compare whisk ferns, club mosses, and horsetails.22.4 Ferns- Describe the characteristics of ferns- Explain the life cycle of a fern122.1 MossesSimilar to first land plantsNonvascular plant belonging to class Musci and division Bryophyta14,000 species- more than any other bryophytemost are tropicalsome can survive dry climatesall need water to complete their life cyclecommon characteristics include:photosyntheticmulticellularsexually reproducingeukaryoticnon-complicated vascular system- water moves cell to cell by osmosis since most mosses are only a few cells thicklive on moist brick walls, cracks of sidewalks, forest floors, shady sides of treesThe Life Cycle of MossesTypical moss alternates between haploid gametophyte (N) and diploid sporophyte stages (2N)Gametophyte stage-Small gametophyte is longest lived part of the life cycleLeaf like photosynthetic structures lack vascular tissue and are usually only one cell thickHave rhizoids on underside to anchor moss Sporophyte stage- usually smaller and attached to the gametophyte Lacks chlorophyll depending on gametophyte for foodFoot of gametophyte anchors it to sporophyte 2Stalk grows up and is topped by a capsuleCapsule (sporangium) is the structure that forms haploid sporesSexual ReproductionProduce two kinds of gametes: egg & spermGametes surrounded by sterile cells that protect them from drying outEggs are large w/ much cytoplasm and immobileSperm are smaller, flagellated and must swim through water to fertilize the eggArchegonium- the egg producing structure of a mossFlask shaped3Forms on branches of gametophyteEach archegonium forms one eggAntheridium- sperm producing structure of a mossPart of the gametophyteSpherical or sausage shapedEach Antheridium produces many spermBecause the sperm must swim from antheridium to archegonium reproduction can only take place when the gametophyte is under waterSperm follow a trail of chemicals released by the egg in the waterAfter fertilization a zygote is formed which undergoes mitosis to become a sporophyteAfter maturation the sporophyte forms haploid spores to begin the gametophyte generationWhen spores are mature the capsule opens and the wind carries off the spores; if it lands in a moist place it sprouts to form a new gametophyteAsexual ReproductionCan occur in two ways:Fragmentation- small pieces are broken off and form a new plantGemmae- (= swelling or bud. Latin) tiny pieces of tissue that can form new gametophytes. Raindrops splash the gemmae off the parent plant and they are carried away to a new area to form new gametophytesMosses and the Ecosystemdecomposerspioneer specieskeep soil moist and prevent soil erosionshelter for insects and animalsnesting materials for birds & mammalsPeat bogs- a wet ecosystem that is formed by large mats of sphagnum (peat moss)4Sphagnum release a chemical that prevents decomposers from growing; this means that the sphagnum decomposes very slowly and will build up eventually turning a pomd into marshy soilUses of peat moss include:- Burnable fuel- Extremely absorbent making it an excellent additive for dry sandy soil- Moist protective cushion for shipping of plants- Used in diapers & bandaids22.2 Liverworts and HornwortsBoth nonvascularBoth alternate between diploid sporophyte generation and haploid gametophyte generationGametophytes are green a leafy producing archegonia and antheridiaSporophytes attached to gametophytesNeed lots of water for fertilizationLiverworts- about 7000 speciesLiver like shape- thought to cure liver diseases in medieval times (called Doctrine of Signatures)5Umbrella shaped structures are antheridia and archegonia are attached to leafy gametophyte producing gametesAsexual reproduction Gametophytes have growing tips that split into branches as it grows along the ground. When older parts die the newer branches live on as independent plantsGemmae are also produced in gemmae cups on upper surface of gametophyte. Rain splashes the gemmae out of the cup. If it washes to a proper location it starts a new gametophyte6Hornworts- about 100 speciesArchegonia and antheridia form inside the plantA cyanobacteria, Nostoc, sometimes lives in cavities in the gametophytePost fertilization zygotes become long horn like sporophytesThese sporophytes are photosynthetic and therefore not totally dependent on the gametophytes→ 6CO2 + 6H2O + Light Energy→ C6H12O6 + 6O2Spores are spread by drying and splitting of the long thin sporangiaNot as closely related as mosses and liverworts 22.3 Seedless Vascular PlantsVascular Plants/Seedless Plants- Vascular tissue allows them live in areas that bryophytes cannot giving them advantages in the competition for light and water- Gametophytes tend to be smaller than the sporophytes- Gametophytes are separate and independent from sporophyteWhisk ferns- (10-13 species) are tropical plants with simple water-carrying tissues. Some areleaflessOne genera grows in Texas, Florida, Louisiana, Arizona, and HawaiiThe other genera grows on islands of the South Pacific Ocean One species resembles straws in a whisk broom7Lack true leaves and rootsPhotosynthesis occurs in green stemsInstead of roots rhizoids are attached to underground stems called rhizomesKnobs on branches are sporophytesGametophytes develop from spores and live just below the surface of the soilLives symbiotically with fungus that lives in the gametophyte rhizoids. The gametophyte gets it nutrients from the fungusNeeds ample water for fertilizationWhisk ferns are the simplest vascular plant and resemble the first vascular land plants. They are among the earliest known vascular plants in the fossil record Club mosses- (1000 species) mostly small plants with small leaves and often grow in damp places (common name is ground pine)Named for club-shaped spore producing


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