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The Angiosperm Life Cycle. Page 63, Judd & Campbell. & Angiosperm synapomorphies ( Archaefructus , 125 MYBP). Archaefructus fossil. Archaefructus Reconstruction.

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the angiosperm life cycle

The Angiosperm Life Cycle

Page 63, Judd & Campbell

& Angiosperm synapomorphies

(Archaefructus, 125 MYBP)

archaefructus reconstruction
Archaefructus Reconstruction

“It lacks sepals and petals and its reproductive organs, interpreted as carpels and stamens, are produced on an elongate stem”

One of the earliest known genera of flowering plants

“Archaefructusis an extinct genus of herbaceous aquatic seed plants with 3 known species”

alternation of generations
Alternation of Generations

In an alternation of generations, “a diploid sporophyte generation gives rise to a haploid gametophyte generation.” -- Raven et al, Biology.

moss not angiosperm life cycle
Moss (not angiosperm) Life Cycle

Sporophyte is

completely dependent on Gametophyte

ptychostomum pseudotriquetrum
Ptychostomumpseudotriquetrum

Dominant haploid gametophyte generation

Diploid sporophyte completely dependent on gametophyte

fern not angiosperm life cycle
Fern (not angiosperm) Life Cycle

Reduction of gametophyte…

Sporophyte now independent of gametophyte.

Gametophyte still persists as free living individual for months to years.

athyrium felix femina
Athyriumfelix-femina

Unlike in mosses, what you see here is the sporophyte generation.

angiosperm life cyle
Angiosperm Life Cyle

Diploid microspore and megaspore mother cells

Mitosis

Haploid

Mitosis to form vegetative and generative cells

(pollen)

Mitosis

slide11

Add into this drawing the microsporocyte label, the microspores (n) and mitosis to form pollen.

4 microspores

Mitosis

alternation of generations with further reduction in the gametophyte
Alternation of Generations with further reduction in the Gametophyte

Diploid microsporocyte mother cell in Pollen sacs

(there are no gametophytes in this picture…)

meiosis
Meiosis

In meiosis, a diploid mother cell produces 4 haploid daughter cells

3 of 4 megaspores degenerate
3 of 4 Megaspores Degenerate

Microgametophyte= male gametophyte

Megagametophyte= female gametophyte

ovule contains the female gametophyte
Ovule contains the female gametophyte

Develops into tegmen

Develops into testa

outer inner integuments
Outer & Inner Integuments
  • Become the seed coat
  • Testa and tegmen are derived from the outer and inner integuments, respectively.
  • Presumably these are protective coverings.
double fertilization
Double Fertilization

Mature female gametophyte consists of 8 nuclei in 7 cells (usually)

nutritive endosperm
Nutritive Endosperm

Endosperm is triploid nutritive tissue for the developing embryo.

mitosis
Mitosis

In mitosis, a mother cell of any ploidy count produces 2 daughter cells of the same ploidy count as the mother cell.

angiosperm synapomorphies
Angiosperm Synapomorphies
  • Seeds produced within a carpel with a stigmatic surface for pollen germination
  • Reduced female gametophyte– usually 8 cells
  • Double fertilization
  • Triploid nutritive tissue called “endosperm”