chapter 22 outline
chapter 22 outline BIOL 1110
Popular in Introduction to Botany
Popular in Biology
This 5 page Class Notes was uploaded by Caitrín Hall on Tuesday January 26, 2016. The Class Notes belongs to BIOL 1110 at University of Connecticut taught by Bernard Goffinet in Summer 2015. Since its upload, it has received 15 views. For similar materials see Introduction to Botany in Biology at University of Connecticut.
Reviews for chapter 22 outline
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 01/26/16
Seedless Plants 22.1 What are plants? Multicellular autotrophs adapted to life on land – Kingdom Plantae Seedless plants include lycophytes & pteridophytes (vascular) and bryophytes (nonvascular) Land plants are embryophytes – early-stage sporophyte (embryo) depends on maternal care Distinguishing Characteristics of Modern Streptophytes (the land plants and their closest algal relatives) Apical meristems, when present, do not produce tissues; zygotes the only diploid cells; Streptophyte algae sporangia absent; spores lack sporopollenin walls Apicaltissueproducing meristems; multicellular sporophytes; sporangia; Embryophytes sporopollenin walled spores; dependent embryos Nonvascular plants No lignified vascular tissue; no true roots, stems, or leaves; sporophytes unbranched, Bryophytes (liverworts, mosses, and cannot grow independently of gametophytes hornworts) Vascular plants Lignified vascular tissue; sporophytes branched and become independent of gametophytes Seedless vascular plants Seeds absent; adventitious roots present; embryonic roots absent Lycophytes Leaves lycophylls Pteridophytes (ferns) Leaves euphylls Seed plants Seeds present; all leaves are euphylls; embryonic roots present Gymnosperms Flowers and fruits absent; seeds lack endosperm Angiosperms Flowers and fruits present; seeds possess endosperm at least early in development Diversity is important in global ecology and human affairs o CO2 in atmosphere decreased; CO2 in organic material increased o Transpiration circulates water 22.2 DNA and fossils help trace the history of plants Phylogenies – branching, tree-shaped diagrams showing relationships and patterns of ancestry; determines order of evolution DNA data reveal relationships of modern plants o From nucleus, mitochondria, chloroplasts Land plants evolved from Streptophyte green algae o Monophyletic group – 1 common ancestor o Streptophytes – combination of embryophytes & streptophyte algae Order of evolution o Streptophyte green algae bryophytes seedless vascular plants seed plants o Bryophytes do not form monophyletic group descended from single common ancestor Liverworts mosses hornworts Unbranched sporophytes Lack water-conducting tissues o Seedless vascular plants: lycophytes and ferns Lycophytes – earliest; include branched sporophytes and xylem with lignin 22.3 Early plant evolution illustrates the concept of descent with modification Evolution of… 1. Sporophyte generation with dependent embryo Possibility: delaying zygote meiosis because of mutation in streptophyte alga Result: small, multicellular diploid sporophyte increase number of cells that undergo meiosis; zygotic life cycle of streptophyte algae embryophytes alternation of generations Evidence for adaptive sporophytes: vascular plants have larger sporophytes than bryophytes; all modern vascular plants are sporophyte dominant 2. Large leaves having branched vascular systems Lycophylls (microphylls) have true leaves but contain 1 unbranched vein Ferns and seed plants have euphylls (megaphylls)– true, large leaves with leaf gap and branched veins (break in vascular tissues above stem) 22.4 Modern seedless plant groups include bryophytes, lycophytes, and pteridophytes Bryophytes Earliest land plants Liverworts, mosses, and hornworts did not come from single ancestor o Liverworts – small, herbaceous plants named for lobed gametophytes o Hornworts – small, herbaceous plants named for upright, horn- shaped sporophytes o Mosses – produce stem and leaf-like structures that form flattened mats Bryophyte bodies are simple o Few-celled gametophytes take up water and minerals directly from soil, air, and water o Lack true stems, roots, leaves, and lignin (limits height) o Grow close to ground anchored by rhizoids - not composed of tissues, but involve similar proteins as absorptive root hairs o Gametophytes grow close to the ground direct water absorption o Sporophytes – less noticeable; consist of… Basal foot embedded in tissues of maternal gametophyte Sometimes a seta (stalk) raised into the air for spore dispersal Sporangium (capsule) – produces/disperses spores; not branched, never independent of gametophyte Produce wind-dispersed spores, breakage, or asexual structures o Germinating moss spores produce mass of green, branched, one- cell-thick filaments (protonema) high SA maximizes water/mineral absorption; gametophore develops if sufficient resources are there Protonema + gametophore = moss gametophyte body o Mature bryophytes produce many gametangia Eggs – produced singly in vase-shaped archegonia Many sperm – produced in elongate antheridia Placental transfer cells occur at junction of embryo sporophyte and maternal gametophyte for resource transfer Maternal care continues until embryos can grow by mitosis into sporophytes o Hornworts and mosses have sporophytes with stomata—moss capsules (sporangium) o Teeth-shaped peristome enhance spore discharge gradually instead of all at once o Asexual reproduction – gemmae break off and are dispersed by wind or water Mosses – diverse, ecologically significant, economically useful o Able to exist in very cold or dry habitats o Peatlands stabilize CO2 levels and climate—moss growth slows when carbon levels drop o Peat mosses harbor microbes that break down methane o Sphagnum – harvested as fuel, soil conditioner, and packing plant roots during shipment o Aesthetic Lycophytes & pteridophytes – modern phyla of seedless vascular plants Lycophytes have simple leaves and magnificent pasts o Tropical plants in tree branches—stems hang downward o Temperate forest floors—upright stems or horizontal stems with downward roots o Leaves are lycoohylls o Sporophylls cluster to form cones o Spores develop into inconspicuous haploid gametophytes (produce antheridia and archegonia) Pteridophytes have conspicuous leaves with branched vascular systems o Ferns are most diverse in the tropics o Ferns often have horizontal rhizomes that grow leaves with extensively branched vascular systems (euphylls) o Compound leaves divided into leaflets o Produce clusters of sporangia known as sori on the back of leaves o Most have aboveground green gametophytes Lycophytes/pteridophytes reproduction o Homospory – all spores are same size and germinate into similar gametophytes; often prevent self-fertilization o Heterospory – two types of spores that differ in size and gender of gametophytes Endosporic – gametophytes inside spore wall and do not grow out Microspores in microsporangia = male gametophytes = pollen grains = microsporophylls Megaspores in megasporangia= female gametophytes = eggs = megasporophylls Chapter Wrap-up Examine and Discuss Self Test 1. What common characteristics set plants (embryophytes) apart from other organisms, including the most closely related green algae. 2. Describe several ways in which each of the following groups of land plants affect human life today: (a) bryophytes, (b) lycophytes, (c) pteridophytes. 3. What is paleobotany? Which plant materials contribute to the formation of plant fossils and where do these materials occur in plants? 4. What are four key events in the evolution of land plants? Approximately when did these events occur in geological time? 5. What is the difference between lycophylls and euphylls? Among the modern land plants, which possess lycophylls and which possess euphylls? Why are bryophytes considered to lack true leaves? 6. Briefly summarize the major characteristics of bryophytes. 7. Briefly summarize the major features of lycophytes.8. Briefly summarize the major attributes of pteridophytes. Applying Concepts 1. Paleobotanists and plant molecular biologists often study relationships between plants. Paleobotanists glean information from fossils, whereas plant molecular biologists obtain information from nucleic acid sequences. What are some strengths and weaknesses of each approach? 2. Mosses and ferns both require liquid water in order to repro- duce. At what stage of the life cycle is water required? 3. This chapter begins with an overview of the process by which land plants evolved from green algal predecessors (streptophyte algae), which mostly occur in aquatic habitats. Name several features that land plants share with their algal relatives. What problems did (and do) land plants face that their aquatic ancestors did not? How have land plants solved these problems?
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'