Plant Evolution & Diversity – Ch. 22-25 BOT 101 Plant Evolution & Diversity – Ch. 22-25

Kingdom Protista: Algae & Protozoa BOT 101 Kingdom Protista: Algae & Protozoa Organisms in this Kingdom don’t fit clearly into what we call plant, animal, or fungi. Most diverse eukaryotic Kingdom (>60,000 species). We are interested in this Kingdom because of the Chlorophytes & Charophyceans - green algae.

BOT 101 The line between Kingdom Protista and Kingdom Plantae is still being discussed…… Fig 29.4

BOT 101 Origin of Plants

Characteristics of Green Algae - Chlorophytes BOT 101 Characteristics of Green Algae - Chlorophytes There are unicellular and multicellular forms Can live symbiotically with fungi as lichens

Fig 28.30 Volvox - freshwater Ulva – sea lettuce Caulerpa - intertidal BOT 101 Fig 28.30 Volvox - freshwater Ulva – sea lettuce Caulerpa - intertidal

Characteristics of Green Algae - Charophyceans BOT 101 Characteristics of Green Algae - Charophyceans fresh water ponds They are considered to be the closest ancestors of true plants. Evidence: . Both form a cell plate during cell division Genetic evidence – charophyceans share a greater % of similar DNA with true plants than any other algae

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BOT 101 Plants So how are they different from Charophyceans??

What challenges did plants face when they “moved” onto land? BOT 101 What challenges did plants face when they “moved” onto land?

Adaptation to life on Land: BOT 101 Adaptation to life on Land: . Multicellular gametangia Multicellular, dependent embryos

BOT 101 1. Apical Meristems –

2. Alternation of Generations BOT 101 2. Alternation of Generations

2 multicellular life stages: Sporophyte: Diploid BOT 101 2 multicellular life stages: Sporophyte: Diploid Divides by meiosis to form spores Spores – haploid cells that can grow into a new, multicellular, haploid organism (the gametophyte) without fusing to another cell. Gametophyte: Haploid Divides by mitosis to form the gametes (egg and sperm) Egg & sperm fuse to form the diploid zygote, which divides by mitosis to form the sporophyte

3. Walled spores produced in sporangia BOT 101 3. Walled spores produced in sporangia Sporopollenin protects the spore from harsh environmental conditions Sporangia = Sporocytes = the diploid cells within the sporangia that divide by meiosis to form the haploid spores

BOT 101 sporocytes

4. Multicellular gametangia BOT 101 4. Multicellular gametangia Gametangia = 2 types of gametangia: Archegonia – Antheridia – Sperm travel to the egg, fertilizing it within the archegonia.

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5. Multicelluar, dependent embryos BOT 101 5. Multicelluar, dependent embryos Zygote divides by mitosis to become the sporophyte.

BOT 101 Other examples of adaptations to life on land: (not all plants have the following): Cuticle – Secondary compounds – Roots – Shoots - stems and leaves to make food. Stomata – openings in the leaf surface to allow gas exchange for photosynthesis and to regulate water loss.

BOT 101 More Adaptations 4. . 5. A vascular system that transports food & water from roots to shoots and vice versa.

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BOT 101 Fig 29.7

Nonvascular Land Plants: Bryophytes BOT 101 Nonvascular Land Plants: Bryophytes Earliest land plants 3 Phyla: Hepatophyta – Anthocerophyta – Bryophyta - . Peat moss (sphagnum): doesn’t decay rapidly, stores 400 bil tons of carbon Gametophyte is the dominant generation:

BOT 101 Moss life cycle Fig 29.8

Phylum Hepatophyta – liverworts BOT 101 Phylum Hepatophyta – liverworts

Phylum Anthocerophyta – hornworts BOT 101 Phylum Anthocerophyta – hornworts

Phylum bryophyta - mosses BOT 101 Phylum bryophyta - mosses

Peat bogs – sphagnum moss BOT 101 Peat bogs – sphagnum moss Fig 29.10

Vascular Plants Vascular tissue: Xylem = water & mineral transport BOT 101 Vascular Plants Vascular tissue: Xylem = water & mineral transport Phloem = food (carbohydrates) transport . Sporophytes branched, independent of gametophyte parent

Seedless Vascular Land Plants BOT 101 Seedless Vascular Land Plants Egg & sperm need moist environment to fertilize (similar to bryophytes)

Two phyla of seedless vascular plants: BOT 101 Two phyla of seedless vascular plants: Phylum Lycophyta (Club Mosses) flammable spore clouds were tree-like in the Carboniferous period

Phylum Lycophyta: clubmosses, spikemosses, quillwarts BOT 101 Phylum Lycophyta: clubmosses, spikemosses, quillwarts

2. Phylum Pterophyta Whisk ferns – Horsetails – BOT 101 2. Phylum Pterophyta Whisk ferns – Horsetails – Ferns – produce clusters (sori) of sporangia on underside of leaves (fronds)

Phylum Pterophyta: ferns, horsetails, whisk ferns BOT 101 Phylum Pterophyta: ferns, horsetails, whisk ferns

BOT 101 Fig 29.12 Life cycle of a fern

Forests of the Carboniferous period (290-360 mil years ago): BOT 101 Forests of the Carboniferous period (290-360 mil years ago): Heat + pressure + time ----> coal Pulled lots of CO2 out of atmosphere, cooling the earth & forming glaciers Larger species died out when climate became drier

Terrestrial Adaptations of Seed Plants BOT 101 Terrestrial Adaptations of Seed Plants Seeds replace spores as main means of dispersal. Why? Gametophytes became reduced and retained within reproductive tissue of the sporophyte Heterospory – Zygote develops into an embryo packaged with a food supply within a protective seed coat. Pollen & Pollination - freed plants from the requirement of water for fertilization.

1. Seeds replace spores as main means of dispersal. BOT 101 1. Seeds replace spores as main means of dispersal. old way (ferns & mosses) = new way: the sporophyte RETAINS its spores within the sporangia & the tiny gametophyte develops within the spore. ovule = after fertilization, the ovule becomes the seed seed = sporophyte embryo + food supply (mature ovule tissues)

2. Reduction of the gametophyte: BOT 101 2. Reduction of the gametophyte: Similar to Fig 30.2

3. Heterospory – separate male & female gametophytes BOT 101 3. Heterospory – separate male & female gametophytes Old way: sporangia  spores  bisexual gametophyte (antheridia  sperm, archegonia -> eggs) New way: Microsporangia  microspores  male gametophyte  sperm

4. Ovules and seed production BOT 101 4. Ovules and seed production Megasporangia protected by layers of tissue called integuments. Ovule = After fertilization, embryo develops, ovule becomes a seed

BOT 101 Fig 30.3

BOT 101 5. Pollen & Pollination Microsporangia  microspores  male gametophyte  sperm Pollen = Pollination = Pollen tube brings sperm to egg within the ovule

Two types of seed plants: 1. Gymnosperms BOT 101 Two types of seed plants: 1. Gymnosperms Evolved first “naked seed” – 2. Angiosperms Evolved from gymnosperms: Sporophylls rolled together to form ovaries.

Gymnosperms Four phyla: Ginkophyta – Cycadophyta – Gnetophyta – BOT 101 Gymnosperms Four phyla: Ginkophyta – Cycadophyta – Gnetophyta – Coniferophyta – Dominate forests of the N. hemisphere Most are evergreen Needle-shaped leaves to reduce water loss during drought

BOT 101 Phylum Cycadophyta

BOT 101 Phylum Ginkophyta

BOT 101 Phylum Gnetophyta

BOT 101 Phylum Coniferophyta

BOT 101 Fig 30.6

Angiosperms One phylum: Anthophyta BOT 101 Angiosperms One phylum: Anthophyta Formerly only 2 classes: monocots & dicots. Now 4 clades (evolutionary lines): Basal angiosperms Magnoliads Monocots Eudicots

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Evolutionary success of Angiosperms due to: BOT 101 Evolutionary success of Angiosperms due to: . Flowers – attract pollinators Fruits – many forms for variety of dispersal mechanisms

BOT 101 Fig 30.3

Notice the triploid stage! BOT 101 Notice the triploid stage! Each pollen grain (male gametophyte) produces two sperm Sperm travel down the pollen tube & into the ovule. Double fertilization – Ovule matures into the seed – contains sporophyte embryo & endosperm (food). Ovary (female sporangium tissues) matures into the fruit.

Kingdom Fungi (A tiny bit of Ch. 21) BOT 101 Kingdom Fungi (A tiny bit of Ch. 21)

But Fungi: their bodies are filamentous BOT 101 But Fungi: their bodies are filamentous the organization of large structures such as mushrooms and morels is completely different from plants, they are heterotrophs (aquire nutrients by absorption) Hence the boot!!

Ecological Roles of Fungi: BOT 101 Ecological Roles of Fungi: Decomposers –

Ecological Roles of Fungi: BOT 101 Ecological Roles of Fungi: 2. Parasites – absorb nutrients from living hosts.

Ecological Roles of Fungi: BOT 101 Ecological Roles of Fungi: Mutualists with plants – . ex. mycorrhizae

BOT 101 Lichens: symbiotic association of cyanobacteria or green algae and fungi. Lichens are very sensitive to air pollution; used as indicators of air quality.

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Lifestyles of Fungi, continued BOT 101 Lifestyles of Fungi, continued Mycorrhizae: mutualistic association of plant roots and fungi. Fungus receives food from the root exudates.

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