The Life history of a Flowering Plant
Now we will look at the life history of a flowering plant. It is very similar to that of a fern except that there are male spores and female spores.
Most of the plants around us are flowering.
Like ferns, the dominant part of the life cycle is the sporophyte.
Flowering plants produce haploid spores. Microspores are produced within
the anthers whereas the megaspores are produced wthin the ovule.
The microspores divide to produce the male gametophyte (pollen).
The megaspore develops into a female gametophyte within the ovule.
The ovule is retained within the ovary.
Within the female gametophyte an egg cell develops. You should be able to identify all
of the components of the pistil; if not a review of the previous section may help.
Pollen is released and distributed by wind or other vector (bees, butterflies, etc).
Some may end up on the stigma of a receptive flower.
The pollen germinates to produce a tube which digests its way through
the stigma and down the style.
……the pollen tube grows, carrying nuclei toward the ovary.
The pollen tube reaches the ovule.
Once the pollen tube is in close proximity to the egg, two sperm
cells are released.
An egg and sperm fuse to produce a zygote. the second sperm fuses
with other nuclei within the female gametophyte. This produces tissue
called endosperm.
The zygote remains in the ovule within the ovary of the pistil.
The zygote develops into the embryo. The ovule becomes the sees; the outer part of the ovule (integument) becomes the seed coat. Where would the endosperm be?
The seed germinates and embryo develops into a new sporophyte.