Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Ornamental bulbous plant wikipedia , lookup
Evolutionary history of plants wikipedia , lookup
Ecology of Banksia wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Perovskia atriplicifolia wikipedia , lookup
Plant reproduction wikipedia , lookup
Flowering plant wikipedia , lookup
Structure and Evolution of Flowers 42.3 Learning Objectives 1. List the parts of a flower 2. Distinguish between bilateral and radial symmetry 3. Differentiate between microgametophytes and megagametophytes Flower Evolution ● Flowers evolved in Angiosperms ● Flowers evolved from leaves ● Floral diversity is result of natural selection of pollination strategies ● Flowers and pollinators have co-evolved Flower Morphology 4 parts (whorls) 1. Calyx ● outermost whorl ● made of sepals ● protect the bud 2. Corolla ● 2nd whorl ● made up of petals ● petals attract pollinators 3. Androecium (Male Parts) ● 3rd whorl ● Stamen ○ male portion of the flower ○ 2 parts ■ Filament ● stalk that bears the anther ■ Anther ● ● group of 4 microsporangia produce pollen (sperm spores) 4. Gynoecium (Female Structures) ● 4th innermost whorl ● known as the Carpel ○ composed of: ■ stigma ■ style ■ ovary ■ ovule Function of the Carpel Parts Stigma ● sticky structure that attaches pollen Style ● slender tube that connects stigma and ovary Ovary ● contains ovules and develops into the fruit Ovule ● eggs that will develop into seeds when fertilized Floral Specialization Complete Flower ● has all 4 whorls present in the flower Incomplete Flower ● lacks 1 or more whorls Or ● whorls have fused together Monocot vs. Dicot MONOCOTS DICOTS Embryo with single cotyledon Embryo with two cotyledons Pollen with single furrow or pore Pollen with three furrows or pores Flower parts in multiples of three Flower parts in multiples of four or five Floral Symmetry 1. Radial Symmetry ● primitive flowers ● can divide the flower in half by drawing a line through the center anywhere 2. Bilateral Symmetry ● more advanced flower groups ○ flowers with precise pollination systems ● can only be divided along 1 line Alternation of generations Microgametophyte= male gametophyte ● pollen grains Megagametophyte = female gametophyte ● embryo sac Sporophyte = fertilized egg (seed) Process of Pollination Steps: 1. pollen is transferred from anther to the stigma (pollination) 2. pollen tube grows down into ovule 3. sperm fertilizes the egg (fertilization) 4. ovule develops into seed 5. ovary develops into fruit Self-pollination