The Seedless Vascular Plants II: The Ferns(Note: this is a long lab, so work efficiently -- about 10 minutes max. per drawing)Division Pterophyta: FernsGenera: Adiantum, Cyrtomium, Polypodium, Asplenium, Pteridium, Botrichium, Ophioglossum, Azolla, Salvinia, MarsileaKey features of the division: Heteromorphic alternation-of-generations life cycle, sporophyte dominant.Have true xylem and phloem, so have true vascularized stemsHave true roots and true leaves (megaphylls)Chlorophyll a, b, carotenoids, starch, cellulose, phragmoplast, oogamy, multicellular gametangiaReproduction and growth less dependent upon water than BryophytesPrimitive groups (Botrychium, Ophioglossum) are eusporangiate, advanced groups are leptosporangiate.Most homosporous, except for heterosporous water ferns (Marselia, Salvinia)Key Features and Terms (prepare a labeled drawing for each numbered item):Eusporangiate ferns (homosporous) Botrychium (Grape or Red Fern) – living specimen1) Vascularized sporophyte with one or a few megaphyllous leaves. Eusporangia in specialized fertile frond.Leptosporangiate ferns (homosporous):Most terrestrial ferns (many examples, including Adiantum, Cyrtomium, Polypodium, Asplenium, Pteridium) – living specimens and herbarium specimens1) Vascularized sporophyte with megaphyllous leaves, sori (with or without indusia) containing groups of sporangia, rhizomes (subterranean stems) bearing roots. Living specimen.2) Leptosporangium with stalk, annulus, and lip cells, bearing (meio)spores (haploid) which were produced by meiosis. Spores dispersed by wind. Slide.3) Rhizome cross section showing siphonostele with leaf gaps, epidermis, cortex, endodermis, vascular cylinder, pericycle, phloem (sieve elements and albuminous cells), xylem (tracheids), and pith. Slide.4) Heart-shaped bisexual gametophyte (haploid) bearing both antheridia (sperm) and archegonia (egg). May be fertilized, thus bearing a young sporophyte. Slide.Water ferns (heterosporous) – photos in text book1) Marsilea rhizomes, aquatic, cloverlike leaves, sporocarps (bean-like resistant 2n structures), germinate in water to form chains of sori, each sorus contains rows of microsporangia and megasporangia2) Azolla float on surface, micro- and mega-sporangia in sporocarp, leaf pouch contains cyanobacteria (nitrogenfixing)3) Salvinia float on surface, micro- and mega-sporangia in sporocarp, two leaves green and photosynthetic, one fertile leaf (sporocarp) dissected and bearing sporangia, hangs down into the water.The Gymnosperms:Division CycadophytaGenus: Zamia (Sago-Palm)Division Ginkgophyta:Genus Ginkgo (Ginkgo Tree)Division Coniferophyta:Genera: Pines (Pinus), firs (Abies), spruce (Picea), hemlocks (Tsuga), Douglasfirs (Pseudotsuga), bald cypresses (Taxodium, Sequoia, Sequoiadendron, Metasequoia), cypresses (Cupressus), yews (Taxus), junipers (Juniperus), and Norfolk Island pine and MonkeyPuzzle (Araucaria).Division GnetophytaGenera Gnetum, Ephedra, WelwitschiaKey features of the group: Heteromorphic alternation-of-generations life cycle, sporophyte dominant.Have true xylem and phloem, so have true vascularized stemsHave woody or semi-woody growth.Produce sporangia in cones (strobili or modified branch complexes)Heterosporous.Have true roots and true leaves (megaphylls)Chlorophyll a, b, carotenoids, starch, cellulose, phragmoplast, oogamy, multicellular gametangiaPolyembryony female (megagametophyte) produces several archegonia. Several eggs may be fertilized and several embryos may begin development.Microgametophytes (pollen) transport sperm to eggs. When contacting the megagametophyte, the microgametophyte germinates to produce a pollen tube. Sperm move down pollen tube, and are flagellated only in cycads and Ginkgo.Reproduction and growth less dependent on water than Seedless Vasc. PlantsMost advanced group is the Gnetophytes, which share characteristics with the Angiosperms: strobili similar to angiosperm flowers, doublefertilization, xylem structure similar, insect pollination common.Key Features and Terms (prepare a labeled drawing for each numbered item): Cycadophyta: Zamia (Sago-Palm)1) Sporophyte with palmlike leaves, pollen and ovules in conelike strobili, dioecious, scant secondary growth. Living specimens.Ginkgophyta: Ginkgo biloba (Ginkgo Tree) 2) Woody sporophyte with fanshaped leaves, deciduous, dioecious, paired ovules at branch tips, ovules may not be fertilized by microgametophyte until after dispersal, fleshy seeds. Herbarium specimen and photos in text book.Gnetophyta - photos in text book1) Gnetum - sporophytes are tropical trees and vines with large leaves2) Ephedra (Mormon Tea, Ma Huang) sporophytes are profusely branched shrubs with reduced scalelike leaves, jointed stems like Equisetum, arid areas (ephedrine)3) Welwitschia - sporophyte with massive central disk, two huge longlived straplike leaves, desert plants, conebearing branches at margin of central disk.Coniferophyta: Pinus (Pines)1) Sporophyte with needlelike leaves bundled into small groups (fascicles). Leaves with central vein (two vascular bundles), endodermis, transfusion tissue, mesophyll, hypodermis, epidermis, stoma and resin ducts. Slide.2) Microsporangia and megasporangia in separate strobili on same tree (monoecious). i) Microsporangium Produce microspores which develop into winged pollengrain (2 prothallial cells, generative cell and tube cell). Tube cell forms a pollen tube after pollination, while generative cell forms two sperm cells. Slide. ii) Megasporangium within seed/scale complexes, ovuliferous or fertile scales each with two ovules and subtending sterile bracts. Ovules have multicellular nucellus surrounded by an integument with a micropyle. Meiosis produces 4 megaspores, 3 of which die. Slide.4) Megaspore grows to form the megagametophyte within nucellus, but is not ready for fertilization until 12 months after pollination. Polyembryony may result if multiple archegonia are present. Diagram in text book.5) Seed 3layered seed coat (2N protective maternal sporophyte [nucellus + integuments] tissue), embryo (2N offspring or new sporophyte tissue), remaining megagametophyte tissue (1N nutrient source). Generally wind dispersal. Some dispersedby fire (explosive) or animals (Clark's Nutcrackers, for example). Slide.6) Embryo hypocotylroot axis, root cap, apical meristems at both ends, multiple cotyledons (seed leaves). Living specimen or diagram in text book. Review Questions (for Lab