Domain Eukarya Kingdom Plantae Phylum Anthophyta/Magnoliophyta Flowering Plants Domain Eukarya Kingdom Plantae Phylum Anthophyta/Magnoliophyta

Life Cycle of Flowering Plants SYNGAMY zygote Sporophyte Gametophyte sporangium sporocyte spores gametangia gametes germination mitosis differentiation 1N 2N 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 ™ carpel gynoecium flower perfect style locule ovary anther ¢ superior stamen pollen ovule filament androecium flower hypogynous petal corolla receptacle sepal complete perianth calyx pedicel

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 Nucleus Cytoplasm Generative Cell Nucleus Cytoplasm The tube cell digests a path from the stigma to the egg. The generative cell follows the path to the egg, and divides to make two sperm cells. Both participate in syngamy. http://images.iasprr.org/lily/pollen2.jpg Pollination: vector-assisted movement of the pollen grain from the anther to the stigma.

The tube cell germinates through the pollen wall. 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 4 megaspores meiosis I meiosis II 3 disintegrate functional megaspore mitotic divisions without cytokinesis 3 antipodals megagametophyte central cell egg cytokinesis 2 synergids

karyogamy! In Flowering Plants, syngamy is a double event: syngamy#2: 2 x 1N polar nuclei + 1N sperm = 3N primary endosperm cell sperm nuclei no miracle-gro, no compost! 1N egg + 1N sperm = 2N zygote syngamy#1: synergids disintegrating In this slide, plasmogamy has already occurred…but what part of syngamy has not occurred yet? karyogamy! http://botit.botany.wisc.edu/courses/img/Botany_130/Diversity/Angiosperms/Fertilization.jpg