Flowering Plants Domain Eukarya Kingdom Plantae Phylum AnthophytaMagnoliophyta
- Slides: 16
Flowering Plants Domain Eukarya Kingdom Plantae Phylum Anthophyta/Magnoliophyta
Life Cycle of Flowering Plants SYNGAMY mitosis gametes zygote gametangia differentiation Gametophyte 1 N 2 N germination mitosis differentiation Sporophyte differentiation mitosis germination differentiation sporangium spores mitosis sporocyte MEIOSIS The flowering plant is a multicellular diploid sporophyte. The sporophyte encloses the multicellular haploid gametophyte. The life history is thus sporic (diplohaplontic). The gametes are oogamous but the sperm lack flagellae. Gender expression has moved from gametophyte to sporophyte.
Flower Organization-building a flower from bottom up A flower is a short shoot (stem with leaves) The stem is represented by the receptacle with very short internodes The leaves appear in four whorls stigma locule ovule flower hypogynous ™ gynoecium flower style carpel perfect anther ¢ ovary superior pollen stamen filament androecium petal corolla receptacle pedicel sepal calyx complete perianth
Microsporogenesis: Prophase I of Meiosis http: //images. iasprr. org/lily/lpachy-m. jpg
Microsporogenesis: Late Prophase I of Meiosis http: //images. iasprr. org/lily/lepto. jpg
Microsporogenesis: Metaphase I of Meiosis http: //images. iasprr. org/lily/meta-i. jpg
Microsporogenesis: Anaphase I of Meiosis http: //images. iasprr. org/lily/anaph. jpg
Microsporogenesis: Telophase I of Meiosis http: //images. iasprr. org/lily/telo-i. jpg
Microsporogenesis: Metaphase II and Anaphase II of Meiosis http: //images. iasprr. org/lily/meta-ii. jpg
Microsporogenesis: Telophase II of Meiosis http: //images. iasprr. org/lily/telo-ii. jpg
Microsporogenesis: Meiosis complete (but prophase of mitosis) http: //images. iasprr. org/lily/tetrad. jpg
Microsporogenesis: Completed, Separated Microspores (note prophase) http: //images. iasprr. org/lily/microsp. jpg
Pollen Grain: Mitosis Makes Endosporic Microgametophyte Pollen Wall: Microspore Wall (allergenic? ) Tube Cell Generative Cell Nucleus Cytoplasm The tube cell digests a path from the stigma to the egg. http: //images. iasprr. org/lily/pollen 2. jpg Pollination: vectorassisted movement of the pollen grain from the anther to the stigma. The generative cell follows the path to the egg, and divides to make two sperm cells. Both participate in syngamy.
Pollen Tube Growth The tube cell germinates through the pollen wall. The cell grows chemotropically toward the egg. The pollen tube must find the ovule’s micropyle. The generative cell slides along this tube. It divides by mitosis to form two sperm cells. http: //bilbo. bio. purdue. edu/~cjslab/pollen-tubes. jpg
Megasporogenesis: taking place inside the ovule inside the ovary. megasporocyte meiosis I 4 megaspores 3 disintegrate meiosis II functional megaspore mitotic divisions without cytokinesis megagametophyte 3 antipodals central cell cytokinesis egg 2 synergids
In Flowering Plants, syngamy is a double event: syngamy#2: sperm nuclei 2 x 1 N polar nuclei + 1 N sperm = 3 N primary endosperm cell no miracle-gro, no compost! syngamy#1: 1 N egg + 1 N sperm = 2 N zygote synergids disintegrating http: //botit. botany. wisc. edu/courses/img/Botany_1 30/Diversity/Angiosperms/Fertilization. jpg In this slide, plasmogamy has already occurred…but what part of syngamy has not occurred yet? karyogamy!