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„ Kingdom Plantae „ Plant or land plants „ Multicellular eukaryotic organisms composed of cells having plastids SSiection 4 „ Primarily live on land Professor Donald McFarlane „ Evolved from green algal ancestors that lived in aquatic habitats Lecture 10 Plants: „ Distinguished from modern algal relatives Colonization of the Land by adaptations to terrestrial life

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Streptophytes

Land plants (kingdom Plantae) (embryophytes)

Vascular plants (tracheophytes)

Euphyllophytes

Seed plants (spermatophytes)

Bryophytes Seedless Green algae (nonvascular plants) vascular plants Gymnosperms Ancestry

0 CENOZOIC Ginkgo Cycads Mosses Hornworts 65 Liverworts Lycophytes gnetophytes Conifers and Conifers Angiosperms Pteridophytes „ Probably originated from a photosynthetic

Other green green Other algae Flowers, fruits,

Simple charophyceans endo- Complex charophyceans sperm MESOZOIC in seeds protist ancestor having a relatively 248

Permian Ovules, pollen, seeds 290 comppylex body Carbon- iferous Euphylls (megaphylls) 354 Devonian Filament of cells with side branches 417 Lignin in walls of water-conducting cells; cutin common on epidermis; Silurian stomata common on plant surfaces; PALEOZOIC 443 dominant sporophyte generation; true roots, stems, leaves „ Ordovician Either Chara or Coleochaete are modern Millions of years (mya) ago Millions 490 Cambrian protists most closely related to ancestry of 543 Sporic life cycle, embryo, sporopollenin-walled spores, tissue-producing apical meristem, gametangia, sporangia, xyloglucans in cell wall

Plasmodesmata, plant-specific features of cell division, eggs and sperm land plants PROTEROZOIC

Chlorophyll a and b, starch produced in plastids KEY 2500 Critical innovations Common protist ancestor a:© Roland Birke/Phototake; b: © The McGraw-Hill Companies, Inc./Linda Graham, photographer; c-e: © Lee W. Wilcox; f: © B. Runk/S. Schoenberger/Grant Heilman Photography; g:© Ed Reschke/Peter Arnold; h: © Patrick Johns/CORBIS; i: © Bob Evans/Peter Arnold; j:© Wolfgang Kaehler/Corbis; k: © Fred 3 4 Bruemmer/Peter Arnold; l: © Gallo Images/Corbis

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„ Complex Distinctive feature of land plants charophyceans share several derived traits with „ Represent early adaptations to land land plants „ Bodies composed of 3D tissues Increased ability to avoid water loss Plasmodesmata „ Tissues arise from apical meristems at growing tips Sexual „ Able to produce thick, robust bodies reproduction using egg and smaller „ Tissues and organs with specialized functions sperm „ Distinctive reproductive features Alternation of generations Dry air resistant reproductive cell Specialized structures to generate, protect, and disperse reproductive cells

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10 plant phyla “bryophytes”

1. Liverworts – Hepatophyta „ Include liverworts, hornworts, and mosses 2. Mosses – Bryophyta 3. Hornworts – Anthocerophyta „ Each forms a monophyletic phyla 4. Lycophytes – Lycophyta „ Share common structural, reproductive 5. Pteridophytes – Pteridophyta 6. Cycads – Cycadophyta and ecological features 7. Ginkgos – Ginkgophyta „ Models of earliest terrestrial plants 8. Conifers – Coniferophyta 9. Gnetophytes – Gnetophyta 10. Angiosperms – Anthophyta

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Sporangium „ Bryophytes display features absent from charophycean algae but present in plants „ Likely early adaptations to land Sporophyte „ Charophycean algae display a zygotic life cycle with a one cell diploid zygote

Gametophyte „ Bryophytes and other plants exhibit a sporic life cycle with alternation of generations

(mniumSEM): © Eye of Science/Photo Researchers Diploid, spore-producing sporophyte generation Haploid, gamete-producing gametophyte generation

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KEY haploid Single-celled diploid diploid (2n) Sperm zygote Multicellular Fertilization haploid (n) gametophyte Spores Meiosis

Mitosis Egg

Mitosis KEY New: Haploid Clarophycean “algae” Haploid spores multicellular Diploid diploid (2n) Meiosis sporophyte

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Sperm Fertilization Multicellular haploid (n) gametophyte Single-celled Adaptations to life on land diploid (2n) Egg zygote

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Spore Mitosis dispersal tip „ Multicellular diploid sporophyte generation

(a) Zygotic life cycle of charophyceans Sporophyte advantageous because it allows a single

KE Y change ry a ppplant to disperse widel yygy by using meiosis Haploid Diploid

Gametophyte Evolution to produce numerous, genetically variable Sperm Multicellular Fertilization Single-celled haploid (n) diploid (2n) zygote haploid spores gametophyte

Mitosis © Lee W. Wilcox Egg „ Each spore has the potential to grow into

Mitosis

New: a gametophyte multicellular Meiosis diploid (2n) sporophyte

(b) Sporic life cycle of early plants

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Gametophytes Sporophytes

„ Role to produce haploid gametes „ Matrotrophy – zygotes remain sheltered and fed within gametophyte tissue „ Produced by mitosis „ Embryophytes – all land plants have „ Gametangia protects developing gametes from matrotroppyhic embryos didrying ou t an d m icro bilttkbial attack „ When mature, spores are produced in protective Antheridia – round or elongate gametangia producing enclosures known as sporangia sperm „ Plant spore cell walls contain sporopollenin to Archegonia – flask shaped gametangia enclosing an help prevent cellular damage egg „ During evolution, plant sporophytes become „ Sperm swim to egg and fuse to form diploid larger and more complex zygote „ Zygotes grow into sporophytes 15 16

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Distinguishing bryophyte features

„ Gametophytes dominant generation As opposed to dominant sporophyte generation in other plants „ Sporophytes are dependent on gametophtye – small and short lived As opposed to independent, large and long- lived in other plants „ Nonvascular or lacking tissues for structural support and conduction found in other plants (vascular plants)

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„ Pteridophytes – about 12,000 species of Lycophytes and pteridophytes horsetails, whisk ferns and other ferns

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. „ Vascular plants that do not produce Sporangia seeds „ Lycophytes- more Stem numerous and

larger in the past Small leaves but now about © Lee W. Wilcox 1000 relatively small species 19 20

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Roots, stems and leaves „ Diverged prior to the origin of seeds Seedless vascular plants „ Stems Contain vascular tissue and produce leaves „ Lycophytes, pteridophytes and seed- and sporangia producing plants are vascular plants or Contain phloem and xylem (contains tracheophytes tracheids and lignin) Possess tracheids for water and mineral „ Roots conduction and structural support Specialized for uptake of water and minerals from the soil Vascular tissues occur in the major plant „ Leaves organs: stems, roots, and leaves Photosynthetic function

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Adaptations That Foster Stable Internal

Water Content Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Life cycle Vascular tissue „ Lycophyte and pteridophyte reproduction is „ Waxy cuticle present on limited by dry conditions, as is the case for most surfaces of vascular bryophytes plant sporophytes Stomate „ However, if fertilization occurs, lycophytes and „ Cutin found in cuticle that Cuticle helps prevent pathogen 120 mm pteridophytes can produce many more spores attack (a) Stem showing tracheophyte adaptations due to their larger sporophyte generation „ Wax prevents dessication Vascular plant sporophytes are dependent upon „ Stomata are pores that Stomata maternal gametophytes for only a short time during open and close to allow early embryo development gas exchange while Stems of vascular plant sporophytes are able to minimizing water loss (b) Close-up of stomata produce branches, forming relatively large adult a: © The McGraw-Hill Companies, Inc./Linda Graham, photographer; b: © Lee W. Wilcox

23 plants having many leaves 24

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25 (sporophyte): © Barrett & MacKay Photography; Companies, Inc. Permission required for reproduction or display

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