Ch 23 Part 2
Phylum Magnoliophyta • Apomixis and parthenocarpy: • Apomixis - Without fusion of gametes but with the normal structures otherwise being involved • Embryo from diploid nutritive cell or other diploid cell of ovule, instead of from zygote. • Results in a vegetatively propagated plant • Parthenocarpy - Fruits develop from ovaries with unfertilized eggs. • Results in seedless fruits • Navel oranges and bananas
Phylum Magnoliophyta • Trends of specialization and classification in flowering plants: • First historical classifications for convenience. • Modern botanists group plants according to natural relationships based on evolution. • Fossil record suggests flowering plants first appeared about 160 million years ago during late Jurassic. • Flowering plants then developed during Cretaceous and Cenozoic. • Dominant plants today
Phylum Magnoliophyta • Trends of specialization and classification in flowering plants: • First pistil from leaflike structure with ovules along margins = carpel. • Edges of blade rolled inward and fused together. • Separate carpels of primitive flowers fused together to form compound pistil consisting of several carpels.
Phylum Magnoliophyta • Inferior ovary (epigynous flower) - Receptacle or other flower parts fused to ovary and grown up around it. • Calyx and corolla appear to be attached to top of ovary. • Superior ovary (hypogynous flower)- Ovary produced on top of receptacle. • Other flower parts attached around ovary base. • Perigynous flowers - Flower parts attached to corolla tube of fused petals, creating floral tube that is not attached to ovary. • Trends of specialization and classification in flowering plants:
Phylum Magnoliophyta • Trends of specialization and classification in flowering plants: • Complete flower - Has calyx, corolla, stamens and pistil • Incomplete flower - Corolla or other flower parts missing. • Perfect flower - Both stamens and pistil present. • Imperfect flower - Either stamens or pistil missing. • Monoecious species - Male and female imperfect flowers on same plant. • Dioecious species - Plant bears only male flowers and other plants bear only female flowers. Male flower Female flower with inferior ovary
Phylum Magnoliophyta • Trends of specialization and classification in flowering plants: • Primitive flowering plants: • Simple leaves. • Flower with numerous, spirally arranged parts, not fused to each other • Flowers radially symmetrical = regular. • Flowers with both stamens and pistils • Complete and perfect flowers • Superior ovary (hypogynous flower) • Still many plants today whose flowers have primitive features. Magnolia
Phylum Magnoliophyta • Trends of specialization and classification in flowering plants: • Specialized flowering plants: • Flower parts fewer and definite in number. • Spiral arrangements compressed to whorls • Bilaterally symmetrical flowers = irregular • Reduction and fusion of parts • Incomplete or imperfect flowers • Inferior ovary Orchid
Pollination Ecology • Pollinators have coevolved with plants. • Twenty thousand bee species among current-day pollinators. • Bee-pollinated flowers: • Generally brightly colored, mostly blue or yellow • Often have lines or other distinctive markings, which may function as honey guides to lead bees to nectar. • Bees see UV light (humans do not). • Some flower markings visible only in UV light. In ordinary light In UV light
Pollination Ecology • Beetle-pollinated flowers: • Strong, yeasty, spicy or fruity odor • White or dull in color - Beetles do have keen visual senses. • Some do not secrete nectar, but furnish pollen or food on petals in special storage cells. • Fly-pollinated flowers: • Smell like rotten meat • Dull red or brown
Pollination Ecology • Butterfly- and moth-pollinated flowers: • Often have sweet fragrances • White or yellow for night-flying moths • Sometimes red, often blue, yellow or orange for butterflies • Nectaries at bases of corolla tubes or spurs for long tongues. • Bird-pollinated flowers (hummingbirds and sunbirds): • Often bright red or yellow • Little if any odor - Birds do not have a keen sense of smell. • Large and part of sturdy inflorescence • Copious amounts of nectar - Birds highly active. • Long floral tubes
Pollination Ecology • Primarily in tropics • Open at night when bats are foraging • Dull in color • Large enough for bat to insert head or consist of ball-like inflorescence containing large numbers of small flowers • Bat-pollinated flowers:
Pollination Ecology • Orchid flowers: • Have pollinators among all types mentioned • Some of adaptations between orchid flowers and pollinators are extraordinary. • Pollen grains produced in little sacs called pollinia (singular: pollinium) with sticky pads at base. • Members of Ophrys have modified petal that resembles female bumble bee or wasp. • Male bees or wasps try to copulate with flower. • Pollinia deposited on their head. Ophrys
Herbaria and Plant Preservation • Herbaria (singular: herbarium) - Libraries of dried, pressed plants, algae, and fungi, arranged and labeled. • Methods: • Fungi and bryophytes dried and stored in small packets. • Plant press used for vascular plants.
Herbaria and Plant Preservation • Methods: • Vascular plant specimens mounted on 100% rag herbarium paper. • Specimens stored so retrieval of specimens is easily accomplished.
Review • Introduction • Phylum Magnoliophyta – The Flowering Plants • Development of Gametophytes • Pollination • Fertilization and Development of the Seed • Apomixis and Parthenocarpy • Trends of Specialization and Classification in Flowering Plants • Pollination Ecology • Herbaria and Plant Preservation
