PLANT REPRODUCTION, continued...

Carpel consists of,
 Stigma - receptive part
 Style
 Ovary - at base of carpel -- houses ovules.

EXCEPTIONS to the 'textbook' flower.

Stamens consist of filaments and anthers.

Carpels are fused, hollow, modified leaves that produce OVULES. Each ovule contains an EGG.
 These are the ‘vessels’ in the word angiosperm, which means 'vessel seed'.
 Flowers often have several carpels each, either  separate or fused together.
  (Remember the chambers in an apple core?)
 Carpel or fused carpels sometimes called a PISTIL. Note: your book uses the term 'pistil' largely in place of carpel.

        Pollination Vectors: think of some.....

Birds, beetles, ants, flies, bats, wasps and flutterbyes....
  ESPECIALLY insects.
Flowering plants have CO-EVOLVED with their vectors.
 Modified structure and physiology to match pollinators.
  Fusion of flower parts to aid insects.
    What else?
 TIME of flower opening, or scent production, keyed to pollinators.  E.g. For nocturnal moths.
 Both flower and insect may have complex life cycles that precisely match each other.
   E.g. Tropical strangler figs.
 Even sexual mimicry, with male bees and wasps trying to mate with flowers, which look and smell like their female counterparts.

 Diversity of flower structure and animal pollination vectors accounts in large part for flowering plant diversity.

Many plants use WIND to disperse pollen.
 Can you think of some?
 How are their flowers specialized? 

Meiosis occurs in anther, ovules. Gives rise to microspores and megaspores.
Microspores divide twice to produce 3 celled pollen; two of cells are sperm. Other is called vegetative cell, or tube cell.
Megaspores divide to produce 7 celled EMBRYO SAC.  
    One of cells is egg.

When pollen lands on stigma, a RECOGNITION process is initiated.
 Pollen must be COMPATIBLE.
        Why can't tomato cross pollinate with marigolds?
        Why in some species can't one plant pollinate itself?

After pollen grain lands on stigma, provided the interaction is compatible, it germinates, growing a tube-like extension --  pollen tube.
 Inside are 2 NONMOTILE sperm.  Fig. 23.7
 
In other words, pollen grain/tube contains THREE haploid cells, including TWO sperm cells that are totally selfcontained within the other larger vegetative cell, which is also haploid. The pollen grain/tube is the MALE GAMETOPHYTE of flowering plants.

                        REMEMBER alternation of generations in plants.
                            How is it related to flowering plant reproduction?

Sperm are passively carried down pollen tube as it grows thru  stigma, style and into ovary.

How are these features adaptations to reproduction by a sessile, terrestrial plant????  What does WATER have to do with it?

Inside ovary are the ovules, attached to wall or central   column.  Figs. 23.3, 23.10

Inside ovules egg is housed in a special structure called the Embryo Sac. Fig. 23.3
    Contains 7 cells -- 6 small cells including the egg, and one large Central Cell, which has TWO haploid, or POLAR nuclei.
        The embryo sac is the FEMALE GAMETOPHYTE

Pollen tube grows into ovary, towards ovule. Fig. 23.3
 It’s attracted to ovule by chemical signals.

Endosperm is genetically distinct from the embryo  -- it's triploid.
 Surrounds embryo. Again, it's serves an absorbtive/nutritive function in seed.