Transcript Botany-Fern
Chapter 21 Lecture Outline The Seedless Vascular Plants: Ferns and Their Relatives Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Outline Introduction– Primitive Vascular Plants Phylum Psilotophyta – The Whisk Ferns Phylum Lycophyta – The Ground Pines, Spike Mosses and Quillworts Phylum Equisetophyta – The Horsetails and Scouring Rushes Phylum Polypodiophyta – The Ferns Fossils Introduction to Primitive Vascular Plants Primitive Vascular plant characteristics: • Internal conducting tissue developed. • True leaves • Roots • Gametophytes are smaller . • Sporophytes are larger and dominant • Primitive: no seeds Four phyla of seedless vascular plants: Psilotophyta, Lycophyta, Equisetophyta, Polypodiophyta Introduction Psilotophyta • Sporophytes have neither true leaves, nor roots. • Stems and rhizomes fork evenly. Psilotum Lycophyta • Plants covered with microphylls. – Microphylls - Leaves with single vein whose trace is not associated with a leaf gap Lycopodium Introduction Equisetophyta • Sporophytes have ribbed stems containing silica. • Have whorled, scalelike microphylls that lack chlorophyll Equisetum Polypodiophyta • Sporophytes have megaphylls that are often large and much divided. – Megaphylls - Leaves with more than one vein and a leaf trace associated with leaf gap A fern Phylum Equisetophyta – The Horsetails and Scouring Rushes Equisetum SPOROPHYTE: • Branched and unbranched forms, usually less than 1.3 meters tall • Stems jointed and ribbed. • Green and do Photosynthesis • If branched, then branches in whorls. • Long-lived Branched Form Silica deposits on walls of stem epidermal cells. Un-branched Form • Stomata in grooves between ribs • Scalelike leaves in whorls at nodes = microphylls; are nonfunctional • Strobili = Non-woody Cones GAMETOPHYTES • Gametophytes lobed, green, cushionlike, up to 8 mm in diameter. • Short-lived • Small • Have Archegonia & Antheridia - make eggs and sperm Phylum Equisetophyta Equisetum reproduction: • Asexual by fragmentation of rhizomes • Sexual reproduction: – Strobili at tips of stems with sporangia produce spores. – Spores green with 4 ribbonlike elaters attached. o Aid in spore dispersal Spores with elaters -- Spores released into ____________ and grow into _______ -- Gametophytes make_____ -- Fertilization = ___________________________and produces _________ Phylum Equisetophyta Equisetum reproduction: Phylum Equisetophyta Human and ecological relevance: STUDENTS DO Reconstruction of fossil giant horsetail, Calamites Phylum Polypodiophyta – The Ferns Sporophyte Structure and form: • Vary in size from tiny floating forms less than 1 cm to giant tropical tree ferns up to 25 m tall – Fern leaves are megaphylls - Referred to as fronds. o Typically divided into smaller segments Phylum Polypodiophyta – The Ferns • Sporophyte is conspicuous phase. – Fronds, rhizomes, roots – Fronds first appear coiled in crozier (fiddlehead), and then unroll and expand. o Fronds often divided into segments called pinnae (singular: pinna). Crozier Phylum Polypodiophyta – The Ferns Reproduction: • Sporangia stalked. – May be scattered on lower leaf surface, confined to margins, or found in discrete clusters called sori (singular: sorus). o – Sori may be protected by indusia (singular: indusium). With row of heavy-walled, Sorus covered by indusium brownish cells = annulus o Annulus catapults spores out of sporangium Phylum Polypodiophyta – The Ferns • Meiosis forms spores in sporangia. GAMETOPHYTES • Spores released and grow into gametophytes called prothalli (singular: prothallus). • Prothalli are one cell thick, and have archegonia and antheridia. Archegonia Antheridia • Require external water for reproduction because: ____ • Zygote develops into young sporophyte. • Gametophyte usually dies and leaves sporophyte growing independently. Phylum Polypodiophyta – The Ferns Reproduction: Phylum Polypodiophyta Human and ecological relevance: • House plants – Function well as air filters • Outdoor ornamentals • Cooked rhizomes as food • Folk medicine • Fronds used in thatching for houses. • Basketry and weaving Fossils A fossil - Any recognizable prehistoric organic object preserved from past geological ages. • Conditions of formation almost always include quick burial and an accumulation of sediments. – Hard parts more likely preserved than soft parts. Review Introduction Phylum Psilotophyta – The Whisk Ferns Phylum Lycophyta – The Ground Pines, Spike Mosses and Quillworts Phylum Equisetophyta – The Horsetails and Scouring Rushes Phylum Polypodiophyta – The Ferns Fossils