There is general agreement that the precursor to the ancestoral flower was a modified whorl of leaves, and that extant flowers with multiple parts of indefinate number probably represent the ancestoral condition. For an interesting discussion on ... The following diagram represents a hypothetical angiosperm life cycle:
www.cartage.org.lb/en/themes/sciences/botanicalsciences... www.cartage.org.lb/en/themes/sciences/botanicalsciences/plantreproduction/Angiosperms/Angiosperms.htm
Within the ovary, the pollen tube enters the ovule and deposits two haploid sperm cells in the embryo sac (see Web Figure 1.2.B). One sperm cell fuses with the egg to ... The vegetative plant represents the diploid sporophyte generation. ... Web Figure 1.2.A Schematic representation of an idealized flower of the angiosperms.
www.plantphys.net/article.php?ch=t&id=18
rather, it gives rise to a 7-celled, 8-nucleate embryo sac. No archegonia are produced. This reduced megagametophyte represents the ultimate in reduction (an ever-present theme in evolution). ... An angiosperm ovule has greater protection via a double integument, plus a specialized food reserve for the developing embryo,
userwww.sfsu.edu/~biol240/labs/lab_12seedplants/pages/a... userwww.sfsu.edu/~biol240/labs/lab_12seedplants/pages/angiosperms.html
The central part of a typical angiosperm flower is the gynoecium that is composed of one (simple pistil) or more (compound pistil) carpels. ... A characteristic pistil has, from bottom to top, an enlarged basal ovary that includes the embryo sac, a columnar style and distal stigma, the organ that receives the pollen.
www.biologie.uni-hamburg.de/b-online/e02/02d.htm
In angiosperms, the dominant sporophyte; Produces spores that develop within flowers into male gametophytes (pollen grains); Produces female gametophytes (embryo sacs); An overview of angiosperm reproduction; Flower Structure; ... Then discharges two sperm into the embryo sac; In double fertilization; One sperm fertilizes...
faculty.valenciacc.edu/tklenk/notes/bio2notes/flowers.h... faculty.valenciacc.edu/tklenk/notes/bio2notes/flowers.htm
The tube nucleus controls the growth of the pollen tube as grows down the style and into the ovary of a flower. ... 28. What is the chromosome number of a polar nucleus inside the endosperm mother cell within the embryo sac? ... 29-32. A hypothetical angiosperm embryo sac (megagametophyte) contains a total of 32 chromosomes.
waynesword.palomar.edu/genxtra1.htm
Angiosperm embryo sac development begins with a phase of free nuclear division followed by cellularization and differentiation of cell types. The indeterminate gametophyte1 (ig1) gene of maize (Zea ... The female gametophyte, or embryo sac, undergoes a stereotypical number of divisions to produce an eight-nuclei syncytium.
www.plantcell.org/cgi/content/full/19/1/46
We previously reported molecular markers showing no recombination with the trait for aposporous embryo sac development in Pennisetum squamulatum and Cenchrus ciliaris, and the collective single-dose alleles defined an apospory-specific genomic ... Although we examined the chromosome number in only four F1 individuals,
www.genetics.org/cgi/content/full/163/3/1069
When you look at an angiosperm in flower you are looking at both diploid (sporophytic) and haploid (gametophytic) phases of the life cycle. The angiosperm gametophytes - ... This 'female' reproductive entity, also known as the 'embryo sac' stays in place within the ovule which is also positioned within the ovary.
www.csdl.tamu.edu/FLORA/Wilson/tfp/repro/tfplec4f99.htm
Williams and Friedman hypothesized that the diploid endosperm and the four-cell embryo sac was the ancestral condition. But Friedman’s 2006 study of Amborella trichopoda, a New Caledonia flower that represents the oldest lineage of angiosperms, ... Though another basal angiosperm, Amborella had a much bigger embryo sac,
blogs.sciencemag.org/origins/2009/04/justintime-provisi... blogs.sciencemag.org/origins/2009/04/justintime-provisioning-of-emb.html