HIGHER PLANTS B K Auti Radhabai Kale Mahila
HIGHER PLANTS • B K Auti Radhabai Kale Mahila Mahavidyalaya, Ahmednagar.
HIGHER PLANTS Topics • Gymnosperms (Cone-bearing) • Angiosperms (Flowering) • Monocots, dicots & flowers
LEARNING OUTCOMES • Gymnosperms-morphology, biology & ecology. • Angiosperms-morphology, biology & ecology. • How do the 2 major groups of angiosperm plants differ? • What anatomical features of angiosperms are involved in their reproduction?
GYMNOSPERMS (PINES AND CONIFERS): MORPHOLOGY, BIOLOGY, & ECOLOGY • Pine tree-sporophyte. • Gametophyte generation-microscopic stages that grow inside tree’s cones. • Cones significant adaptation to land-harbour all of conifer’s reproductive structures. • Pine tree bears two types of cones: • Female cone-larger, hardy, woody. • Male-smaller, soft, short-lived.
LIFE CYCLE OF GYMNOSPERM
ANGIOSPERMS (FLOWERING PLANTS): MORPHOLOGY, BIOLOGY, & ECOLOGY • Displays sex life. • Flowers display plant’s male and female parts and are sites of pollination and fertilization. • Generate fruits, which contain seeds.
LIFE CYCLE OF AN ANGIOSPERM
Angiosperm life cycle resembles that of gymnosperms. • Similarity: plant-sporophyte and tiny gametophyte generation lives on it. • Contrast: gymnosperm-gametophyte grows in cone and seeds are naked. Angiosperm-gametophyte in its flowers and seeds produced in an ovary and packaged inside fruits.
Other features that enhanced success of angiosperms • Evolution of mutually dependent relationships with animals (carry pollen more reliably then wind). • Ability to reproduce rapidly (fertilization occurs 12 hours after pollination, making it possible for plant to produce seeds in few days or weeks). Gymnosperms usually take years to produce seeds.
STRUCTURE OF FRUIT REFLECTS FUNCTION IN SEED DISPERSAL • Fruit-ripened ovary of a flower. Special adaptation that disperses seeds. • Dependence on wind for dispersal e. g. dandelion fruit. Acts like a kite. • Fruits that hitch a ride on animals e. g. cockleburs. • Fleshy edible fruits contain seeds that get dispersed in animal’s (consumer) feces.
INTERACTIONS WITH ANIMALS-PROFOUNDLY INFLUENCED ANGIOSPERM EVOLUTION • Flowering plants and land animals have mutually beneficial relationships throughout their evolutionary history. • Most angiosperms depend on birds, insects and mammals for pollination and seed dispersal. • Most land animals depend on angiosperms for food. • Mutual dependency improves reproductive success of both and thus is favoured by natural selection.
Bees are attracted to flowers that have markings that reflect UV light. As bee feeds on nectar, it picks up pollen.
Flowers that attract birds have nectar located deep in floral tube where only the long, thin beak and tongue of that bird can reach. Picks up pollen on beak and feathers while feeding.
• Some flowering plants depend on nocturnal pollinators such as bats. • These plants have large, light-coloured highly scented flowers that can be easily found at night. Anther dusts bat’s hair with pollen and passes onto other flowers.
HOW DO THE 2 MAJOR GROUPS OF ANGIOSPERM PLANTS DIFFER? • Two main groups of angiosperms: monocots and dicots • Monocot and dicot refer to the first leaves that appear on plant embryo. • These embryonic leaves are called seed leaves, or cotyledons. • Monocot embryo-one seed leaf. • Dicot embryo-two seed leaves.
A COMPARISON OF MONOCOTS & DICOTS
WHAT ANATOMICAL FEATURES OF ANGIOSPERMS ARE INVOLVED IN THEIR REPRODUCTION?
OVERVIEW: THE SEXUAL LIFE CYCLE OF A FLOWERING PLANT • Flower-sepals, petals, stamens, carpels. • Sepal-before flower opens, sepals enclose and protect flower bud. • Petal-advertises flower to insects and other pollinators. • Flower’s reproductive organs: stamen and carpel. • Stamen-male organ. • Carpel-female organ. • Ovary-base of the carpel. Houses ovules. • Ovule-contains developing egg and cells that support it.
LIFE CYCLE OF A GENERALIZED ANGIOSPERM
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