PHOTOSYNTHESIS, conclusion

Some closing words about photosynthesis vs. respiration, and the second law of thermodynamics,
  uphill and downhill

PLANT REPRODUCTION

      (Make sure to read chapters 8 AND 23 in your book)

THINK OF THE ITSY BITSY SPIDER...

In animals, sex largely occurs as organisms meet.
  In plants, organisms not locomotory; can’t ‘meet’.
 In animals, sex based on BEHAVIOR.
  In plants, sex is very much a function of growth  and development.
  In plants, gametes must get together by intermediaries, or VECTORS.
 In animals, germ line set aside in embryo.
  In plants, no defined germline. Gametes form on  vegetative structure, at various times.

I.e., How do plants ‘DO IT’?
 As in animals, sexual reproduction is the main strategy.
 As in animals, outcrossing (I.e. no inbreeding) is important.
So, how do plants ‘do it’, if they’re SESSILE, terrestrial organisms?
    Clearly, they need intermediates to get male sperm from flower on one plant to flowers on another member of the same species some distance away. VECTORS.
    By taking advantage of a variety of vectors, by CO-EVOLVING with them, flowering plants have 'blossomed' in species diversity.

Remember: evolution tends to narrow niches, eliminating competition. The same applies to pollination vectors.

Once upon a time, around 150 million years ago... what happened???

The ANGIOSPERMS are the most diverse group of plants.
  Greater than 250,000 species known.
 Most diverse geographically too.

The success of angiosperms is in large part due to the flower.
 And the story of the flower is in large part the story of how to do sex on land if you can’t  MOVE.
    Again, it's about vectors.

What is a flower?   Fig. 8.5
The flower is just the product of a shoot apical meristem which stops producing vegetative organs (leaves, lateral buds) and starts producing floral organs. Usually, when it’s done, it also stops being a meristem. It’s ‘all used up’.

Shoot apical meristem produces flower parts in WHORLS, or concentric layers or rings.

 sepals outermost
 petals
 stamens
 carpels (pistil)

Sepals cover and protect the flower. They’re usually green, but they can be colored like the petals.

Petals are often, but not always, brightly colored.

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.

Carpel consists of,
 Stigma - receptive part
 Style -- EXTRA: CAN  YOU THINK OF A PLANT WITH VERY PROMINENT STIGMA/STYLES???????
 Ovary - at base of carpel -- houses the ovules

Think about the picture I showed of the fossil 'flower'.
   What was the arrangement of carpels like compared to modern flowers?
     What changed and how?

       After fertilization, each ovule becomes a SEED.

EXCEPTIONS to the 'textbook' flower.