Ch. 23 Seedless Vascular Plants BIO 1010 FA23-2.pdf

Chapter 23 The Seedless Vascular Plants: Ferns and Their Relatives Learning Objectives 1. 2. 3. 4. 5. Summarize the features that distinguish seedless vascular plants from bryophytes. Contrast microphylls and megaphylls Compare the generalized life cycle of a homosporous plant with that of a h...

Chapter 23 The Seedless Vascular Plants: Ferns and Their Relatives Learning Objectives 1. 2. 3. 4. 5. Summarize the features that distinguish seedless vascular plants from bryophytes. Contrast microphylls and megaphylls Compare the generalized life cycle of a homosporous plant with that of a heterosporous plant. Summarize current classification of pteridophytes. Name and describe the plants in Phyla Lycopodiophyta and Pteridophyta 6. Describe the life cycle of Selaginella sp. 7. Describe the generalized life cycle of a fern. 8. Discuss some of the ethnobotanical importance and uses of seedless vascular plants. Simple Plant Cladogram Seeds Flowers, double fertilization, endosperm and fruit Megaphylls Apical Growth Vascular Tissue Embryo Protection • Analyzes primitive and derived characters • A clade is an evolutionary branch that includes a common ancestor and all descendants Seedless Vascular Plants: Pteridophytes ❖ Slightly more advanced❖ Have vascular tissue to move water, nutrients and photosynthates characteristics ❖ Sporophyte dominant ❖ Vascular tissue: (independent and free ❖ = true roots, stems and leaves living) ❖ Often still prefer moist environments ❖ Only spores & need water for sexual reproduction ❖ Apical and upright growth ❖ Homosporous & Heterosporous Gametophyte Stage becoming Reduced Bryophytes Seedless Vascular Plants Seeded Vascular Plants Gymnosperms Angiosperms 5 Evolution of a transport system→ Vascular tissue • Composed of two complex tissues: • Xylem – water and minerals • Phloem – sugars and other metabolites Microphylls and Megaphylls single strand of vascular tissue a. Microphyll One branch began to dominate the stem system. branched vascular tissue Megaphyll The side branches flattened into a single plane. branched stem system Tissue filled in the spaces between the side branches. megaphyll leaf b. Megaphyll evolution process Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 Microphyll Megaphyll Vascular bundle Vascular bundle • Homosporous: only one equally sized spore type • Heterosporous: two spores types, different sizes • Microspore → microgametophyte → sperm • Megaspore → megagametophyte → egg • Monoecious: “one house”, both male and female reproductive organs on one plant • Dioecious: “two houses”, male and female reproductive organs on separate plants, resulting in male plants and female plants Homosporous Plants (Sporophytes) OR Monoecious Gametophytes Gametophyte with male and female gametangia Dioecious Gametophytes Female Male gametophyte gametophyte with female with male gametangia gametangia Homosporous Scenario #1: Monoecious Gametophyte zygote Monoecious Gametophyte Homosporous Scenario #2: Dioecious Gametophyte (Dioecious Gametophytes) egg Homosporous Scenario Comparison Heterosporous Plants (Sporophytes) megaspore Female gametophyte with female gametangia microspore Dioecious Gametophytes Male gametophyte with male gametangia Monoecious Sporophytes: both male and female reproductive organs on same plant OR Dioecious Sporophytes: male and female reproduction on separate plants (sporophytes) Heterosporous: always Dioecious gametophyte zygote Megasporangium with megaspores Single spore type Microsporangium with microspores homosporous heterosporous BIO 1010 Classification of Vascular Plants Tracheobionta (subkingdom) Seedless Vascular Lycopodiophyta Seed (Vascular) Plants Pteridophyta • Club Mosses • Lycopodium sp. • Horsetail rush • Equisetum sp. • Quillworts • Isoetes sp. • Whisk Ferns • Psilotum sp. • Spike Mosses • Selaginella sp. • Ferns • many taxa Gymnosperms Angiosperms Modified from PPG Seedless Vascular Plants – Pteridophytes Phylum Lycopodiophyta Diversity Phylum Lycopodiophyta – Club Mosses, Spike Mosses, and Quillworts ❖ Sporophytes with microphylls. ❖ Representative Genera • Lycopodium sp. (club moss) • Selaginella sp. (spike moss) • Isoetes sp. (quillwort) Lycopodiophyta - Club Mosses, ground pines ❖ Lycopodium sp. – ❖ homosporous ❖ Produce strobilus with sporophylls Lycopodium sp. Strobilus Lycopodium sp. Strobilus Lycopodiophyta Lycopodium sp. Life cycle Lycopodiophyta – Lycopodium sp. gametophyte This species gametophyte has a subterranean, non-photosynthetic and saprophytic. Lycopodiophyta - Club Mosses ❖ Lycopodium sp. reproduction: • In others species, gametophytes develop on surface and are green. Lycopodiophyta - Club Mosses Lycopodium appressum Local Lycopodium sp. Lycopodium obscurum L. Lycopodium alopecuroides L. Lycopodium sp. Ethnobotany ❖ Lycopodiophyta – Selaginella sp. Spike Mosses • Especially abundant in tropics • Branch more freely than ground pines • Heterosporous • Ligule at the base of microphylls Local Selaginella sp. Selaginella apoda L. Selaginella acanthonota Selaginella rupestris Selaginella sp. Ethnobotany Resurrection Selaginella lepidophylla Lycopodiophyta – Isoetes sp. (Quillworts) ❖ Single extant genus ❖ Aquatic to semi-aquatic ❖ Cosmopolitan distribution ❖ Sporangia at base of leaves (quills) Homosporous or heterosporous??? Lycopodiophyta ❖ Ancient relatives of club mosses and quillworts: • Dominant members of forests and swamps of Carboniferous, 325 mya – Large, tree-like, up to 30 meters tall Lepidodendron Surface of Lepidodendron, showing microphyll bases Seedless Vascular Plants – Pteridophytes Phylum Pteridophyta Diversity Phylum Pteridophyta – Ferns: megaphylls • Whisk Ferns – Psilotum sp. Pteridophyta – Equisetum sp. (Horsetail rush) ❖ One Genus, ~25 species ❖ Reduced megaphylls ❖ Wet marshy habitats globally ❖ Silica in cell walls ❖ Strobilus with Sporangiophores ❖ Branched or unbranched Pteridophyta - Horsetail rush Stem Anatomy Pteridophyta Horsetail rush Equisetum sp. Lifecycle Pteridophyta - Horsetail rush: Equisetum reproduction Sporocytes (2n) (l.s.) Pteridophyta - Horsetail rush : Equisetum reproduction Spores with elaters Pteridophyta - Horsetail rush Equisetum sp. reproduction Gametophyte Horsetails in the Carboniferous Landscape Reconstruction of fossil giant horsetail, Calamites Pteridophyta - Psilotum sp. (Whisk Ferns) Considered reduced ferns • Resemble small, green whisk brooms • Erect, dichotomously forking stems • Vascular tissue but no true roots, lost leaves, no strobili, rhizomatous • sporangium Psilotum sp. Pteridophyta - Psilotum sp. (Whisk Ferns) Pteridophyta - Psilotum sp. (Whisk Ferns) Homosporous or heterosporous??? Pteridophyta - Psilotum sp. (Whisk Ferns) • Synagium - Three fused sporangi. Spores Pteridophyta - Psilotum sp. (Whisk Ferns) archegonium from spores beneath ground. • Associated with mycorrhizae fungi Antheridium • Gametophytes develop Psilotum sp. Ethnobotany Spores used by ancestral Hawaiians as a talcum powder to prevent chafing and as a medicinal purge Hawaiian word: moa Pteridophyta - Ferns ❖ aka Polypodiophyta ❖ ~46 families (-aceae) • 200 - 300+ genera Christmas Fern (Polystichum acrostichoides) Crozier (Fiddlehead) Ophioglossum sp. (adder’s tongue fern) Tree Fern ❖ ❖ ❖ ❖ ❖ ❖ Pteridophyta - Ferns Herbaceous perennials Rhizomatous Mostly homosporous, but some heterosporous Segmented Megaphylls (fronds) Require external water for reproduction Free living gametophyte Pteridophyta - Ferns Crozier (fiddlehead) Pteridophyta Ferns Pteridophyta - Ferns Fertile Spikes Pteridophyta - Ferns • Sorus (plural - sori) may be protected by an indusium (plural: indusia) or naked Lacks indusia Pteridophyta - Ferns ❖ Sorus contain many sporangia • Annulus Pteridophyta - Ferns • Spores released and grow into free living gametophytes called prothalli (singular: prothallus). • Prothalli are one cell thick, and have archegonia and antheridia. Pteridophyta - Ferns • Sporophyte growing out of the gametophyte Pteridophyta – General Fern Lifecycle ❖ Local Ferns Bracken Fern Cinnamon Fern Woodwardia sp. Ethnobotanical Uses of Ferns • Some are edible at the fiddlehead stage • Azolla sp associated with cyanobacteria Anabaena • Grown in rice paddies and fertilizes rice plants • Estimated that it converts more atmospheric nitrogen than all of the legumes • Used in Chinese medicine • Extracts used as insecticide Phylum Pteridophyta– The Ferns ❖ • Fossil relatives of ferns: Devonian, 375 mya, Possible ancestors of ferns – Resemble ferns in growth habit, but look more like whisk ferns Possible ancestors: Aglaophyton and Psilophyto Phylum Pteridophyta – The Ferns ❖ Fossil relatives of ferns • Carboniferous, 320-250 mya - Tree ferns abundant and large – Seeds found on some of fossil tree ferns. Questions? Longitudinal section (l.s.) Cross section (c.s. or x.s)