1Biology 101Biology 101Fall, 2008Fall, 2008Week 3 – FlowersWeek 3 – FlowersFlower parts1. The gynoecium (female) 1. The gynoecium (female) Flower parts are arranged in 4 whorls21. The gynoecium (female) ovarystylestigmapistilcarpelFlower parts are arranged in 4 whorls2. The androecium (male) Flower parts are arranged in 4 whorls2. The androecium (male) antherfilamentstamen3Flower parts are arranged in 4 whorls2. The androecium (male) 1. The gynoecium (female) 1. The gynoecium (female) 3. The corolla (petals) Flower parts are arranged in 4 whorls3. The corolla (petals) Flower parts are arranged in 4 whorls2. The androecium (male) 1. The gynoecium (female) 1. The gynoecium (female) 3. The corolla (petals) 4. The calyx (sepals)44. The calyx (sepals) Flower parts are arranged in 4 whorls2. The androecium (male) 1. The gynoecium (female) 1. The gynoecium (female) 3. The corolla (petals) 4. The calyx (sepals) All four whorls areattached to the receptacleandroeciumreceptaclecalyxgynoeciumcorolla5pedunclereceptaclepetals (corolla)antherfilamentstamen(androecium)styleovarystigma(carpels)pistil(gynoecium)ovulesepals (calyx)perianthcorollaFlowersFLOWERS, FRUITS and SEEDSAngiosperms: vessel-seeded vessel: gynoeciumovarycarpel(pod)6Central cell nucleiInflorescence Types7Gynoecium Perigynous receptacleOvules attached to placenta of ovary Placentation : pattern of ovule attachment free central axile parietalCARPEL  Carpel derived evolutionarily from leaves Gynoecium types: Simple Complex8OVULE ovule functions as: megasporangium megagametophyte embryo sacMEGASPOROGENESIS ovule / megasporangium nucellus megaspore mother cell (2N) [meiosis] → 4 megaspores (1N)MEGAGAMETOGENESIS functional megaspore  3 mitotic divisions → eight nuclei 2 polar nuclei 3 antipodal cells 2 synergids 1 egg9DOUBLE FERTILIZATION pollen tube penetrates micropyle one sperm fuses with egg cell → 2n zygote one sperm fuses with polar nuclei →triploid (3n) endospermBiology 101Biology 101Fall, 2008Fall, 2008Fruit and SeedFruit and SeedSEED endosperm + other nutritive tissues + embryo + seed coat mitotic divisions of zygote → embryo  mature (fertilized) ovule10The endosperm and parental tissues from the carpel, together with the embryo, form the seed.However, the maternal tissues are often retained after fertilization and become part of what we commonly call a fruit.Thus, botanically, a fruit is any ovary and its accessory parts that has developed and matured.The ovary wall (pericarp) often gives rise to three regions as it matures:exocarp: the skin of the fruit; originally the outer layer of the mature ovary wall (pericarp)mesocarp: the fleshy part of the fruitendocarp: the interior region endocarp: surrounding the seedsFertilization is usually a prerequisite for fruit development, but treatment with hormones can induce seedless fruit formation.seedPOMES11Types of fruits include:Simple fleshy fruits - develop from a flower with a single pistil.Drupe - simple, single seed enclosed by a stony endocarp e.g. peach, plum, cherryBerry - from a compound ovary, commonly have >1 seed e.g. tomato, grapePome - simple, fleshy fruit largely composed of an enlarged floral tube, e.g. appleAggregate fruits - derive from a single flower with several to many pistils, e.g. blackberryMultiple fruits - derive from many individual flowers in a single inflorescence, e.g. mulberry, figDRUPESPeachesAlmondsOlivesBERRIESGrapesTomatoes12AGGREGATE FRUIT - BlackberryCOMPOUNDFRUITOsage orangeOvaries of many flowers become united13SEED GERMINATIONprimary growth from apical meristems of root (radicle) and shoot  energy for growth from:  endosperm cotyledons (storage proteins)14Bean seed structure, germination and seedlingEMBRYO AND SEEDLING cotyledonarynode  epicotyl hypocotyl radicleCorn seed structure, germination and seedling15Biology 101Biology 101Fall, 2008Fall, 2008Week 3 – Angiosperms-FlowersFruit and SeedHormones, TropismsWeek 3 – Angiosperms-FlowersFruit and SeedHormones, TropismsGROWTHOrientation of growth is determined by microfibrils, whose orientation is determined by microtubules. Colchicinedisrupts microtubules but not microfibrils, resulting in spherical cell growth.Cell enlargement and cell division are regulated separately. Enlargement requires both loosening of the cell wall and positive turgor pressure.Growth is an irreversible increase in the size of an organism or its parts through the use of metabolic energy.DEVELOPMENTSince roots, stems and leaves of many species of plants have basically the same organization, it is logical to believe that similar processes are used in their development.Differentiation reflects the orderly processes by which genetically identical cells become different, forming specialized tissues and organs.16Dedifferentiation is the reversal of cell specialization. It is important in the repair of injury, where cells near damaged sites become totipotent and reprogram their development.Tissue culture is the application of plant growth regulators to mimic the above processes.• Polarity (directionality expressed as differences between different sides or ends of a cell, organ or whole plant) is controlled by the environment in combination with the genome. It is changed only with difficulty in angiosperms.17• Asymmetry is often associated with development, e.g. in the formation of pollen and of stomata from epidermal cells. Localized accumulation of Ca2+ions often precedes and predicts asymmetric cell division.18Electric currents enter pollen tubes and roots at their tips and exit laterally behind tips. Abolition of the current abolishes polar growth.Position determines form and function of flowers, leaves and branching, often in mathematical patterns. Development is also affected by neighboring cells and by cellular location within a tissue or plant, but the processes involved are not understood.19Biophysical factors: Physical pressure or restraint can affect growth patterns -- e.g. microfibrils.•Genetic factors: It is now known that certain genes are responsible for growth patterns -- e.g. Knotted-1.•Timing: Different developmental responses may result from timing, e.g. effect of hormones may differ if applied late or early in development.Modules may exist within standard parts, e.g. the radicle, hypocotyl and cotyledon of an embryo.Modular growthThis may help in grafting