Download Bryophytes: Liverworts, Hornworts and Mosses.

Bryophytes: Liverworts, Hornworts and Mosses. Bryophytes Plant scien+sts recognize two kinds of land plants  Bryophytes, or nonvascular plants  Tracheophytes, or vascular plants. Distribu+on tropical rainforests, arc+c tundra, and desert boulders  Non marine species  Important ini+al colonizers  Important bioindicators Chlorophyta and Bryophyta Charophyta  Chloroplasts with grana  Disintegra+on of nuclear membrane during mitosis  Phragmoplast during cytokinesis  Oogamus sexual reproduc+on  Zygotes remain aFached to the parental thalli  The parental cells develop transfer cells involved in bringing sugars to the zygote  Plasmodesmata Bryophytes and other land plants. Kingdom Plantae  Antheridia and archegonia covered with a sterile jacket layer   Reten+on of the zygote within the archegonium.   Mul+cellular diploid sporophyte   Produc+on of sporogeneous +ssue   Tissues produced by an apical meristem. Bryophytes. Non vascular plants Specialized cell for conduc+on Not lignified cells Large free living gametophyte Sporophyte  Achlorophyllous  Parasi+c on the gametophyte  Unbranched  One sporangium Plasmodemata Bryophytes. Non vascular plants Cu+cle Pores Rhizoids Disk-­‐shaped plas+ds in the thalli One plas+d in reproduc+ve cells Apical and reproduc+ve cells of many bryophytes have a single chloroplast. hexagonal leaf cells with central pore ReproducAon of Bryophytes Asexual: • Fragmenta+on • Gemmae Sexual: • Antheridia • Archegonia • Gametpohytes are haploid • Gametes produced by mitosis Bryophytes need water for fer+liza+on to occur. archegoniophore (female sex organ) ReproducAon of Bryophytes The sperm is aFracted through chemotaxis Matrotrophy Placenta Transfer cells with extensive branched cell walls Apoplas+c Charophyte Sporophyte of bryophytes. Sporophyte of mosses and hornworts contain stomata and two guard cells. • Increase transpira+on • brings up nutrients from the gametophyte through the placenta. • Uptake of CO2 for photosynthesis. Spores covered with sporopollenin.  Cellulose  xylan  lignin  Lipids Extremely resistant to decay and chemicals Charophyte zygotes are lined with sporopollenin Bryophyta:Phylums/Divisions   HEPATOPHYTA -­‐ the Liverworts   ANTHOCEROPHYTA -­‐ the Hornworts   BRYOPHYTA -­‐ the Mosses HEPATOPHYTA (hepaAcs) -­‐ the Liverworts The Liverworts (wyrt= herb) 6,000 Gametophytes develop directly from spores but some produce protonemata Gametophyte  leafy  thalloid Dorsoventrally flaFened Thalloid liverworts Branching is dichotomous Apical meristem Differen+a+on of the thallus into 1.  an upper photosynthe+c region with air chambers 2.  a ventrally storage zone with abundant lipid reserve and rhizoids. Thalloid liverworts Marchan'a produces the sex organs in •  Antheridiophores  antheridia. •  Archegoniophores  archegonia. The sporophyte Short foot Seta Sporangium. Elaters to help in scaFering the spores. Fragmenta+on Gemma cups Leafy liverworts 4000 species 3 rows of isomorphic leaves dorsiventral forms Leaves generally are monostroma+c Antheridia produced on the androecial branches. The archegonium is surrounded by the perianth. ANTHOCEROPHYTA -­‐ the Hornworts 100 species Gametophy+c thallus lobed or dichotomous single chloroplast with pyrenoid in each cell small chloroplasts and no pyrenoids The thallus has internal chambers with Nostoc Rhizoids are unicellular Stomata Most species are bisexual. . Gametangia develop from superficial cells but never project above the surface Sporophyte: Foot embedded in the gametophyte Long capsule or sporangium. intercalary meristem between the foot and the capsule meristem remains ac+ve indeterminate growth photosynthe+c BRYOPHYTA -­‐ the Mosses 12,000 species Classes: Sphagnidae (peat mosses), Andreaeidae (granite mosses) Bryidae (true mosses) Protonema Mul+cellular rhizoids Gametophyte • Leafy with more than three ranks of blades • Chlorophyllous • May or may not branch. BRYOPHYTA -­‐ the Mosses Axis with thick walled outer cor+cal cells and a central strand of smaller cells. Midrib composed of several layers. Hyaline cells Stomata present on the sporangial wall. Paraphyllia Gametophores usually unisexual BRYOPHYTA -­‐ the Mosses Archegonia in the capitulum  apical (acrocarpous) Archegonia in the capitulum branch  on reduced branches (pleurocarpous) Class Sphagnidae Diverged earlier in moss evolu+on. Protosphagnales appear about 290 million years ago in the Permian. Sphagnum has apical gametangia Sporophyte capsules develop on the pseudopodia BRYOPHYTA -­‐ the Mosses “explosive” operculum  closes the opening of the sporangial capsule Sphagnum can absorb water up to 20 +mes its dry weight Sphagnum releases large amount of H+ Peat stores large amount of organic carbon that is not readily released as CO2 Class Andreaeidae 101 species granite or calcareous rocks in northern la+tudes Rhizoids consist of two rows of cells Sporophyte • Foot • Capsule  four valves that open when is dry and close when is moist. Class Bryidae Protonema  uniseriate branched system that precedes the gametophores.  major photosynthe+c role. Mul+cellular rhizoids present • Hadron (water) • Lepton (food) Photosynthe+c lamellae and paraphyllia Some moss stomata are bordered by one doughnut-­‐shaped guard cell The sporangium opening with peristome.