Seedless Vascular Plants: Ferns & Relatives (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 heteros...

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