BIOL 220 - Plant Structure and Reproduction PDF

Lecture 1 - The Plant Cell History of Cell Theory and Microscopy - Cells discovered by Robert Hooke in cork bark in 1665 ​ - Used term “cell” because they reminded him of a monk’s cell ​ - Observed dead cells - Hooke used microscope developed by Antoine van Leeuwenhoek ​ - Small g...

Lecture 1 - The Plant Cell History of Cell Theory and Microscopy - Cells discovered by Robert Hooke in cork bark in 1665 ​ - Used term “cell” because they reminded him of a monk’s cell ​ - Observed dead cells - Hooke used microscope developed by Antoine van Leeuwenhoek ​ - Small glass ball magnified 300x ​ - Leeuwenhoek discovered microorganisms - General theory about nature/ significance of cells ​ - In 1838, Matthias Schleiden confirmed plant parts are composed of cells ​ - In 1839, Theodor Schwann confirmed animals are also composed of cells - Schleiden and Schwann Cell Theory ​ 1. Organisms are made up of one or more cells ​ 2. Cell is basic unit of structure for all organisms ​ 3. New cells arise from existing cells ​ → All are true with exception of viruses - Light microscopes increase magnification as light passes through lenses, includes compound and dissecting microscopes ​ - Can be equipped to observe fluorescence of excited fluorescent compounds ​ - Epifluorescent microscopes use xenon arc or mercury vapour lamps ​ - Confocal microscopes use lasers - Electron microscopes use beam of electrons to visualize samples ​ - Transmission microscope: need specimen to be thin ​ - Scanning microscope: can observe surface of thick specimens The Plant Cell - Cell consists of ​ 1. Cell membrane ​ 2. Nucleus ​ 3. Cytoplasm - Cell membrane is semi-permeable and controls movement of substances in and out of cell ​ - Fluid and flexible, mostly phospholipid bilayer - Phospholipid bilayer made of hydrophobic (water fearing) fatty acid tails and hydrophilic (water loving) phosphate heads ​ - Carbohydrate chains help cell recognition and support ​ - Plasma membrane separates interior from exterior cell environment ​ - Organelles are surrounded by one or two cell membranes - Nucleus is site of DNA storage and translation ​ - Nucleolus in centre synthesizes ribosomes ​ - Surrounded by nuclear envelope, a double membrane ​ - DNA is stored specifically in the nucleoid - Cytoplasm is all cell contents excluding nucleus ​ - Cytosol is fluid in cell ​ - Protoplasm is cytoplasm and nucleus (entire cell) - Protoplast is living cell within cell wall or plant cells that have had their cell walls enzymatically removed - Cytoplasmic organelles ​ - Ribosomes: site of protein synthesis that read mRNA ​ - Endoplasmic reticulum: transportation system and protein folding - Golgi arranged into dictyosome (plant) or golgi apparatus (animals): modifies proteins from ER and packages into vesicles - Mitochondria: performs aerobic respiration to produce ATP ​ - Vesicles: contain liquid or cytoplasm, used for storage or transport ​ - Plastids and central vacuoles are in plants but not animals ​ - Should know these organelles are here, but are not major part of course - Plastids make or store food and/ or pigments in plants and protists - Leucoplasts are pigment-free plastids that synthesize and store starch, oil, and protein - Chromoplasts are pigmented and are responsible for tissue colour ​ - Chlorophyll is green ​ - Carotenoids are yellow, orange, or red ​ - Anthoxanthin is yellow - Chloroplasts are chromoplasts with chlorophyll pigment ​ - Interconversion: plastids can move between different types of plastids ​ - Proplastids are undifferentiated plastids - Mature vacuole makes of 90% of the volume of a mature plant cell - Appear to be empty, but store ions, water, and pigments, sequester toxic compounds, form crystals in specialized cells, and break down organelles and large macromolecules - Vacuole is in center of cell and other organelles are pushed towards cell wall - Vacuole helps maintain cell shape and provides “backbone” via turgor pressure - Cell wall is organized complex of polysaccharides (carbohydrates) and proteins ​ - Rigid and non-permeable ​ - Prevents water loss and provides structural support - Cellulose is main component of microfibril bundles, plus: - Hemicelluloses: carbs that crosslink cellulose microfibrils - Pectins: carbs that gel and regulate cell-cell adhesion - Glycoproteins: sugar proteins that aide in cell-cell adhesion - Primary cell wall is facing external and internal environment - Middle lamella is pectin layer that binds neighbouring primary cell walls - Desmotubules are tube-like extensions formed by ER of neighbouring cells ​ - Allows cells to share contents and signals - Cytoskeleton is network of thread-like proteins found in cytoplasm  - Influences cell division, organelle anchoring and movement ​ - Three main components ​ 1. Microtubules ​ 2. Microfilaments ​ 3. Intermediate filaments - Role of intermediate filaments is not well defined Lecture 2 - First Life in the Water What is a Plant? - Standard nomenclature ex. Homo sapiens or Homo sapiens and H. sapiens or H. sapiens - To be considered a member of the Kingdom Plantae, an organism must: ​ 1. Be multicellular eukaryote 2. Produce own food with photosynthesis (phototroph) using chlorophyll a, b pigments and storing it as starch 3. Be non-mobile (gametes are exception) 4. Have protoplast surrounded by cellulose based cell wall that shares cytoplasm via desmotubules 5. Perform asexual and sexual reproduction - Taxonomy in the 18th-20th century focused on physical appearance and fossil records, while now we use DNA sequence homology - DNA sequence homology is limited to studying surviving, known organisms; ancestors can be lost to extinction - Kingdom Protista is no longer favoured, but the term “protist” is still used - Clades are created based off similarities in genetic sequence - Displayed in phylogenetic trees or cladograms, which are hypotheses about evolution (not fact) Prokaryotes & Eukaryotes - 3.5 - 4 billion years ago, first forms of life (prokaryotes) appear on Earth - Since all living things were derived from common ancestor, they share some characteristics: ​ - Nucleic acids ​ - Proteins ​ - Carbohydrates ​ - Lipids (phospholipid bilayer, plasma membrane) - Common ancestor was prokaryote: single-celled and lacks nucleus and membrane-bound organelles - Two domains within prokaryotes are bacteria and archaea - Most bacteria are heterotrophic (cannot produce their own food) - Cyanobacteria are group of marine and fresh water phototrophs, commonly called “blue green algae”, but are NOT algae - Photosynthesis occurs on thylakoid membranes and transforms solar energy to biochemical energy - Biochemical energy is used to convert CO2 and H2O into sugars, and oxygen is released as a by-product - Cyanobacteria have thylakoid membranes arranged in flattened sacs, but no organelles - Pigments bound to thylakoid membranes can be: chlorophyll (green), carotenoids (yellow, orange, red), or phycobilins (blue) - Form “blooms” in nutrient rich waters, producing cyanotoxins that are dangerous to animals - Responsible for the Great Oxidation Event 2.4 - 2 billion years ago - Cyanobacteria and eukaryotic phototrophs both perform photosynthesis is a similar manner even though their ancestors diverged early on - Endosymbiotic theory: originated as prokaryotes that invaded another prokaryotic cell - Endosymbiotic relationship example: some sea slugs can eat photosynthetic algae and filter chloroplasts to store in guts and allow slug to photosynthesize Protists: Algae - Don’t fully meet criteria of plant - do not have full complexity (leaves, stem, roots) ​ - Considered to be a thallus: a vegetative body - Phycology: the study of algae - Algae used to be grouped based on colour of their pigment - Chromophyta can be multicellular or unicellular, and include yellow-green algae, golden brown algae, diatoms, and brown algae ​ - Brown algae are the least closest of algae protists to land plants ​ - Chlorophyll c in plastids ​ - Fucoxanthin is a xanthophyll pigment which is typically yellow - Undergoes Secondary Endosymbiosis: when a eukaryotic cell engulfs another eukaryotic cell that has undergone primary endosymbiosis - Sea foam is from dead unicellular diatoms - Brown algae (kelp) are multicellular and have cell walls which contain a sugar called algin, and have great environmental importance - Rhodophyta are multicellular and include red algae - Have red phycobiliproteins which good at capturing as much light as possible, allowing it to live in very deep waters - Cells have double cell walls, where outer cell walls contain polysaccharides (sugars) agarose and agaropectin, and inner walls are composed of cellulose - Source of iodine and food - Chlorophyta includes green algae, but was later broken down into to phyla: chlorophyta (chlorophytes and prasinophytes), and streptophyta (charophytes and embryophytes) ​ - Chlorophyll a and b - Can have pyrenoids: compartments that concentrate CO2 for photosynthesis ​ - Prasinophytes ​ ​ - Marine and unicellular ​ ​ - Motile (up to 8 flagella) ​ ​ - No cell walls ​ ​ - Have on chloroplast and one mitochondrion ​ ​ - Plankton ​ - Chlorophytes ​ ​ - Mostly freshwater, motile, and non-motile - Unicellular, colonial, and multicellular - Cellulose-pectin to glucoprotein based cell walls ​ - Charophytes ​ ​ - Closely related to plants - Chara sp. were once thought to be closest common ancestor to terrestrial plants - Coleochaete sp. were also once thought to be closest common ancestor - Zygnematophyceae are now believed to be closest common ancestor - Septated filaments, and perform sexual reproduction via conjugation - Cellulose based cell wall with desmotubules - Develop phragmoplast and cell plate during mitosis - Have cells that resemble leaf cells with multiple chloroplasts - Sexual reproduction  Lecture 3: Green Algae & Bryophytes Challenges Faced by Green Algae - Life was believed to be only in water until 600 million years ago - Animals evolved 600-700 mya, but did not move to land until 425 mya - Fungi are first terrestrial colonizers - Fungi kingdom includes mushrooms, yeast, and moulds - More closely related to animals than plants - Do not perform photosynthesis - Do not have cellulose-based cell wall, instead have chitin - Discovery of fungal fossils in Canadian Arctic suggest terrestrial life may have started 1 billion years ago - In water, algae are protected from desiccation, ultraviolet radiation, fluctuations in temp, and are able to directly absorb nutrients ​ - How do they stay protected when nonmotile and on dry land?​ ​ - Have mechanisms to prevent sun damage and avoid drying out - UV radiation is harmful to all organisms (damages DNA, proteins, lipids in membranes), and not used in photosynthesis - Photodamage: excess visible light leads to reactive oxygen species and damage to photosynthetic machinery in plastids and potentially cell death ​ - Violet and blue have highest energy and can cause most damage ​ - Red has lowest energy - 600 mya, Earth’s magnetic field temporarily weakens, causing hydrogen atoms to escape atmosphere, resulting in more free oxygen ​ - Ozone layer forms, filtering out UV light - Most sunlight cannot penetrate past 200 meters of open water - Sunlight on land would be too much for algae accustomed to filtered light of deeper waters ​ - Algae growing in shallow fresh waters would be more accustomed to light - Freshwater green algae have advantages over marine algae in adapting to land - Green algae live closer to surface and have Charophyte (streptophyte algae) accumulate carotenoid pigments - Carotenoid pigments act as sunscreen, absorbing excess levels of damaging light - Takes away energy from photosynthesis, but protects - Freshwater algae form “soil crusts” which allow them to almost completely dry out and later re-hydrate ​ - Form just under soil surface, protecting them from dangerous UV light - When leaves change colour in fall, the chlorophyll has been broken down, and the carotenoids and anthocyanins are the only pigments that remain - Lichen is a composite organism, a combination of algae and fungi ​ - Fungal portion is on outside, providing a protective layer and anchor ​ - Algae portion is on inside, performing photosynthesis Sexual Reproduction - New gene combinations occur in 3 ways: ​ 1. Union of egg and sperm cells ​ 2. Recombinate as a result of crossover in meiosis I 3. Segregation at meiosis I randomly assorts chromosomes into daughter cells - During metaphase, crossover of alleles which results in exchange of DNA - Phragmoplast is cylinder of microtubules, actin filaments, and ER that forms during cell division - Microtubules trap golgi vesicles containing cell wall materials and membrane to form cell plate - Plants can reproduce quickly via vegetative reproduction or diversify via sexual reproduction - After mitosis, two identical diploid cells - After meiosis, four unique haploid cells - In algae, dominant life form is haploid (one copy of alleles) Bryophytes: Nonvascular Plants - Phylum Hepaticophyta (liverworts), Bryophyta (mosses), and Anthocerophyta (hornworts) - Have similar structure to leaves or stems called thalli (thallus) - No roots, instead have rhizoids - Asexually reproduce via fragmentation - Gametophyte is dominant form - Non-vascular, instead absorb water from cell surfaces and have simple conducting tissue - Have carotenoids to block damaging UV rays - Similarities to vascular plants: - Protected male and female reproductive structures ​ - Multicellular zygote protected in female ​ - Sporophyte produces spores by meiosis ​ - Hornworts have stomata for gas exchange ​ - Mosses have waxy cuticle on epidermis to prevent water loss - Liverworts ​ - Growth is prostrate (flat, dense mats) ​ - Most have flattened, leafy thalli - Mosses ​ - Three classes: peat, rock, and true mosses ​ - Grow low to ground and have waxy cuticle ​ - “Leaves” have blades always one cell thick ​ - Can survive extreme environments by desiccation and dormancy - Hornworts ​ - Closest common ancestor to vascular plants ​ - Sporophyte has stomatal pores for gas exchange ​ - Chloroplast containing a pyrenoid  Lecture 4 - Vascular Plants Life Cycle of Bryophytes: Moss - Majority of moss and algae’s life is spent in gametophyte (1n) phase ​ - Multicellular gametangia at apices ​ - Produce mitotic male gametes in antheridium ​ - Produce one female gamete (egg) in archegonium ​ - Gametes can be produced on one plant or distinct male and female plants ​ - Water is required for sexual reproduction - Sporophyte (2n) phase is the product of fertilization ​ - Sporophyte remains attached to gametophyte ​ - Gives rise to gametophytes through meiosis (haploid spores) - Spores (1n) hydrate in water and develop into filamentous protonema - Protonema can be male, female, or both - Gametophytes form rhizoids - Archegoniophores at apices of “leafy” female gametophytes contain archegonia and paraphyses - Each archegonium contains one egg, stalk attaches structure to base, and neck contains narrow canal that allows sperm to enter - Paraphyses are multicellular filaments scattered among archegonia for protection - Antheridiophoes at apices of “leafy” male gametophytes contain antheridia and paraphyses - Each antheridia contains thousands of flagellated sperm cells - Stalk attaches to the base - Paraphyses scattered among antheridia for protection - Archegonia releases substances to attract sperm cells - In the presence of water, sperm cells are released from antheridia in antheridiophores, enter archegoniophores and swim down neck canal to fertilize egg - Zygote (2n) results from fusion of egg and sperm cell ​ - Grows into multicellular embryo via mitosis - Top of archegonium splits off and forms cap of sporophyte, the calyptra (1n) - Sporocyte meiosis produces spores (1n) inside capsule, released when operculum breaks down Seedless Vascular Plants - Don’t need to know “euphyllophytes” term - Lycophyta is a seedless vascular plant, but not in the ferns and allies group - 350 - 300 mya Carboniferous Period where land is filled with coal forests ​ - Lots of water but plants faced competition for light and nutrients - SVPs dominated Earth, as they grew taller than bryophytes by developing better conducting tissues and stronger cell walls with lignin - Lignification: replaces water and encrusts cellulose with lignin, strengthening primary cell wall - Allows plants to grow upright and taller, increasing light access and protection from predators - Lignin allows increased preservation of tissues and tracheophyte fossil records - Developed vasculature with phloem and xylem - True leaves and roots for absorption and anchorage ​ - No flowers or seeds - Sporophyte (2n) is dominant, and gametophytes become smaller - Phylum Lycophyta: Club Mosses ​ - Stems have microphylls (needle-like leaves) - Result from enations (non-vascularized flaps of tissue) becoming vascularized ​ - Ground pines have true roots which develop along rhizomes ​ ​ - Sporangia housed in strobili, which are modified microphylls (leaves) - Phylum Psilophyta: Whisk Ferns - True roots which develop along rhizomes, associated with mycorrhizal fungi for nutrients ​ - Have no leaves, only spores at the tops of dichotomous branching stems ​ - No leaves, only enations along stems - Phylum Equisetophyta: Horsetails and Scouring Rushes ​ - Branched and unbranched forms ​ - Sporophyte (2n) stems jointed and ribbed ​ - Silica deposits in epidermal cell wall hardens stem in addition to lignin ​ - Spores with ribbon-like elaters attached aide in dispersal - Phylum Polypodia: Ferns ​ - Most successful of the SVPs, grow in damp forests ​ - Have megaphyll leaves like seed vascular plants  - Most have pinnate leaves called fronds: leaves attached to either side of central stem - Fronds first appear coiled in crozier, then unroll and expand - Sporophytes (2n) are dominant - Upon hydrating, spores grow into gametophytes called prothalli ​ - One cell thick, and have archegonia and antheridia - Water required for fertilization, as sperm cells need to swim to archegonium - As sporophyte matures, gametophyte dies and sporophyte grows independently - Stalked sporangia on underside of leaf are found in clusters called sori Introduction to Seed Plants: Gymnosperms - First evidence of SVPs and seed plants 350 mya - End of Carboniferous Period 300 mya, marked by Pangaea formation and mass extinctions - 250-150 mya Triassic and Jurassic Periods were in “Mediterranean Climate”, hot and dry environment ​ - Some SVPs, but gymnosperms dominated by being bigger - Four living phyla, most have strobili (cone structure) - Developed vascular system which is more efficient than ferns - Undergo secondary growth - Phylum Cycadophyta ​ - Slow-growing plants in tropics and subtropics ​ - Tall, unbranched trunks with crown of large pinnately divided leaves ​ - Beetle pollinators ​ - Large seed strobili meters long - Phylum Gnetophyta ​ - Includes some shrubs and vines ​ - Found in arid deserts and are drought tolerant - Phylum Ginkgophyta ​ - Only one living species, was once thought to be extinct ​ - Broad, fan-shaped leaves with no midrib, veins radiate - Dioecious, separate male and female producing plants, but can switch between the two - Fleshy seeds with gross odour - Phylum Pinophyta (conifers) ​ - Largest living group of gymnosperms - Specialized leaves (needles) and vasculature allow them to thrive in cold, dry climates - Invest in large size and long age - As neck length of sauropods increased, so did the size of conifers Lecture 5 - Vascular Seed Plants Life Cycle of Gymnosperms: Conifer - Seed refers to the fertilized, mature ovule that contains ​ - An embryo ​ - Stored food reserves ​ - A protective seed coat - Seeds are built to protect embryos, so when they are consumed it is often an advantage so the plant can spread - Seed can be dormant and wait for right conditions to germinate - Most conifers produce woody female seed cones to protect developing ovules - Males have delicate, papery cones located at the top of tree for protection and dispersal - Some conifers have fleshy coated seeds ​ - Not true fruit; flesh derived from integuments - Most are monoecious - males and females are developed on same plant - Strobuli are at different locations to promote cross-pollination between different individuals - Microsporophylls are the papery part of the male cone which have a microsporangium sac containing microsporocytes - Meiosis produces microspores after mitotic division which develop into pollen grains - Pollen grains are made of four cells and a pair of air sacs for buoyancy - First year of seed maturation: ​ - Pollen grains land on fluid from micropyle from ovule - Pollen grains germinate: pollen tube emerges from pollen grain, entering through micropyle and digests nucellus, producing 2 sperm cells in pollen tube - Megaspore development after pollination: megasporocyte undergoes meiosis, producing four megaspores (one survives), ovule is sealed off from further pollination - Megaspore develops into female gametophyte with two archegonia (each containing one egg) at micropyle end - Nucellus (2n) provides food for developing gametophyte - Integument (2n) provides protection for maturing ovule - Second year of seed maturation: ​ - Pollen tube moves toward archegonia, digesting nucellus ​ - One sperm per pollen tube fuses with egg in archegonium, forming zygote - If pollinated with more than one pollen grain, can fertilize more than one egg at a time ​ - Wing forms from ovuliferous scales and aides in wind dispersal - If no pollination occurs, the female gametophyte will not form ​ - Production of gametophyte takes months ​ - Conserves energy - Two years from pollination to seed production - Bryophytes vs seedless vascular plants vs seed vascular plants: Life Cycle of Angiosperms - Evolved 175 million years ago - 65 million years ago, asteroid collided with the Earth and dust covered the sun, affecting all living organisms - No tetrapods over 55 pounds survived (except for crocodiles and turtles) - Now the age of the mammals - Angiosperms are the most abundant group of plants - Evolutionary innovations leading to land domination: ​ - Improved conducting tissue ​ - More efficient venation ​ - Deciduous leaves ​ - More diverse and specialized leaves - On average, smaller size and/ or shorter life span - Development of flowers and fruit - Annual plants complete life cycle in single season - Biennial plants complete life cycle in two growing seasons - Perennial plants can have life cycle spanning many growing cycles - Strategies to spread quickly: ​ - Co-evolved with pollinators ​ - Seed production is must faster than gymnosperms ​ - Fruit aide in seed dispersal - Do not need to know life cycle - Pedicel is stalk that supports flower and flower parts that attach at receptacle - Corolla contains all petals - Calyx contains all sepals - Perianth contain all petals and sepals - Tepals are when petals and sepals are indistinguishable - Stigma is where pollen lands - Style is where pollen travels through - More primitive flowers (superior ovary) have receptacle, while advanced flowers (inferior/ half-inferior ovary) have hypanthium - Ovary houses the ovule ​ - Ovule contains megasporangium - For males, megasporangium is produced in the anthers - Megaspore production occurs regardless of pollination ​ - Not concerned about energy conservation - Whole reproduction process takes hours to days - Triploid endosperm (3n) is food storage for developing seed Flower Evolution - Carpals fuse to form pistils - may contain more than one ovule - Incomplete flowers are the result of specialization - More advanced flowers have reduced number of parts and are in multiples of 3 - Major trends in flower evolution: ​ - Radial symmetry gives way to bilateral symmetry ​ - Move from tepals to sepals and petals ​ - Spiral arrangement to concentric whorls (circles), which decrease ​ - Transition from superior to inferior ovaries ​ - Reduction, fusion, or loss of floral parts ​ ​ - Carpels fuse to form compound pistil ​ ​ - Styles reduced, fuse with pistil ​ ​ - Complete flowers to incomplete or imperfect flowers Lecture 6 - Fruits and Pollinators Flower Specialization & Families - Primitive flowers have superior ovaries - Ovary produced on top of receptacle with other parts attached around ovary base - Half-inferior ovary is in the middle of evolution towards inferior ovary ​ - Only roses have this ​ - Flower parts attached at top of corolla tube ​ - No longer attached at base of ovary - More advanced flowers have inferior ovaries ​ - Hypanthium fully encloses ovary ​ - Other flower parts are attached at top of ovary - Ranunculaceae (buttercups) are primitive ​ - Often radial symmetry with varying numbers of petals - Many whorls of stamen and carpels (no compound pistil) with superior ovaries ​ - Nearly all herbaceous (annual) ​ - Fleshy fruit are poisonous to animals - Papaveraceae (poppies) are also primitive ​ - Herbaceous in temperate and subtropical regions ​ - Numerous stamens but single pistil (fused carpels) with superior ovaries ​ - Comprised of once two separate groups - Rosaceae (roses) are fairly primitive ​ - Radial symmetry, five petals, five sepals, spirals of many stamen ​ - Many fruit blossom plants and trees ​ - Half-inferior ovaries ​ - Basal parts fused into cup, hypanthium ​ ​ - Many flower parts attached to cup’s rim - Solanaceae (nightshades) are in the middle ​ - Fused corolla that form a “bell” ​ - Many have narrow corolla tube ​ - Superior ovary in pistil composed of two fused carpals ​ - Includes many important native agricultural plants - Asteraceae (sunflowers) are advanced ​ - Florets arranged in compact inflorescence (head) ​ - Individual flowers are florets that have inferior ovaries ​ - Second largest flowering plant family - Cucurbitaceae (pumpkins) are advanced ​ - Prostrate or climbing herbaceous vines ​ - Fused corolla and are unisexual, imperfect flowers ​ - Female flowers with inferior ovary ​ - Includes many important native agricultural plants - Fabaceae (legumes) are advanced ​ - Flowers have bilateral symmetry and stamens fused into tube around ovary ​ - Fruit is a legume, important crops ​ - Third largest flowering plant family - Orchidaceae (orchids) are advanced ​ - Largest family of flowering plants ​ - Many are epiphytic, live on bark - Flowers vary in size and form, but all have bilateral symmetry, fused floral parts, and inferior ovaries - Specific adaptations between orchid flowers and pollinators ​ - E.g. paths for insects to follow - Poaceae (grasses) are the most advanced ​ - Nearly all cereals and sugar cane ​ - Abandoned pollinators and rely completely on wind ​ ​ - No showy perianth or nectar ​ - Earliest fossils, 55 mya ​ - Calyx and corolla are tiny scales and stigmas are exposed and feathery Pollinator Ecology - Depending on plant species, nectary glands can be found on perianth, stamen, carpel/ pistil or receptacle ​ - Location of glands determines which pollinator flower attracts - Plants do not need nectar, they only use it to attract pollinators - Nectar renewal varies by flower and their desired pollinator - Animals change appearance to attract mates, flowering plants change appearance to attract pollinators - Beetles were one of the first pollinators; most have mandibles but some have specialized nectar feeders - Flowers are bowl-shaped with exposed stigma and anthers, nectary glands near surface - Flowers that attract beetles tend to be: - Strong smelling (beetles don’t have good sense of smell) - White or yellow in colour (beetles can’t see colour) - Primitive flowers - Bees are among the best pollinators, and are attracted to flowers based on colour, smell, and electric field ​ - Flowers pollinated by bees tend to be: - Fragrant and sweet smelling - Have nectary glands close to flower surface (bees have short tongue) - Brightly coloured but not red (bees cannot see red) - Perianth often marked to indicate location of nectary glands - Flies and mosquitos can also be pollinators ​ - Less hairy and less efficient pollinators ​ - Have proboscis for accessing nectary glands ​ - Flowers tend to be: ​ ​ - Pale and dull, or dark brown or purple - Smell like rotten meat, dung, or blood - Butterflies have proboscis (long tongue) that can access nectary glands at base of long pistils/ carpels and corolla tubes near receptacle ​ - Butterflies are diurnal (active during day) ​ - Flowers tend to be: ​ ​ - Fragrant and sweet smelling during day ​ ​ - Brightly coloured (may be red, as butterflies can see red) - Moths also have proboscis ​ - Moths are nocturnal ​ - Flowers tend to be: ​ ​ - Fragrant and sweet smelling at night ​ ​ - White or yellow in colour (moths cannot differentiate colour in dark) - Humming birds and sun birds have narrow beaks for accessing nectar ​ - Flowers tend to have: ​ ​ - Bright red or yellow colour with minimal odour (birds cannot smell) ​ ​ - Copious amounts of nectar (birds are highly active) ​ ​ - Long pistils and corolla tubes ​ ​ - Sun birds favour sturdy perches - Bats are not elegant, but are hairy to move pollen ​ - Flowers are: ​ ​ - Primarily in tropical rainforests ​ ​ - Open at night (bats are nocturnal) ​ ​ - Dull in colour ​ ​ - Large enough for bat to insert head ​ ​ - Produce large amounts of nectar and replenish next night ** - know pollinators and how plants are adapted for them - Natural selection strengthened mutual beneficial relationship ​ - Disadvantage: if one side of partnership fails, both struggle Fruit: Development and Function - Fruit is the fleshy or dry ripened ovary that encloses seed - Fruit is not nourishment for seeds, it only aides in dispersal - Basic anatomy: - Dry fruit is by wind dispersal, do not eat - Fruit maturation involves cell division and expanding ovary tissue ​ - Fruit ripening is programmed cell death - In fleshy fruits, cellular components are broken down to produce sugars - Photosynthetic chlorophyll is also broken down for recycling, leaving behind carotenoids - In dry fruits, ripening also involves breakdown of chlorophyll as well as dehydration - Mesocarp is fleshy at maturity, attract animals to eat - Placentation - ovule arrangement: - Drupes form from single flower ​ - Single seed enclosed by hard pit (endocarp) - Develop from single carpel with parietal placentation, of a single flower with superior ovary - Many pits contain cyanide - Berries form from single flower - Form from pistil (fused carpels) of a single flower with more than one seed and fleshy pericarp (no hard pit/ endocarp) - Three groups of berries: 1. True berries: thin skin, includes tomatoes, grapes, peppers, blueberries, and bananas - axile placentation 2. Pepo: thick rind, includes pumpkins and cucumbers - parietal placentation 3. Hesperidium: leathery skin containing oils, includes citruses - axile placentation - Pomes form from single flower ​ - Form from enlarged hypanthium of half-inferior ovary (roses) ​ - Core is papery endocarp that protects seeds ​ - Seeds contain cyanide ​ - Free central placentation - Aggregate forms from single flower - Flesh of fruit made up of many drupe ovaries on swollen receptacle arranged on single flower - Seeds mature on swollen receptacle - In strawberries, ovaries of drupe ovaries merge with fleshy receptacle - Includes strawberries and raspberries - Multiple fruits form from multiple flowers - Fruits form from several separate drupe flowers in an inflorescence, fruits merge to form single fruit - Includes mulberries, osage orange, pineapples, and figs - For dry fruits, mesocarp is dry at maturity ​ - Indehiscent fruits do not split at maturity ​ ​ - Rely on squirrels and other animals for dispersal ​ - Dehiscent fruits split at maturity ​ ​ - Open when fruit dries out, releasing seeds - Siliques are common in herbaceous wildflowers, each silique contains hundreds of seeds  Timeline - 3.5 - 4 billion years ago, first forms of life appear on Earth, eukaryotes - 2.7 billion years ago, cyanobacteria appear in fossil record - 2.4 - 2 billion years ago, Great Oxidation Event caused by cyanobacteria - 2.1 - 1.8 billion years ago, first eukaryotes appear, protists - 1.1 - 1.6 billion years ago, first phototrophic eukaryote - 600 million years ago, ozone layer forms, allowing green algae to transition from water to land - 450-500 million years ago, oldest plant fossils (bryophytes) - 425 million years ago, animals moved to land - 350 million years ago, SVPs dominated during Carboniferous Period - 250-150 million years ago, gymnosperms dominated during Triassic and Jurassic - 175 million years ago, first evidence of angiosperms - 65 million years ago, Pangea separated, causing warmer climate and angiosperm domination