FLOWERS and FRUITS

Angiosperms is the name given to plants that produce flowers. The flower contains the reproductive organs of a plant.

Male Reproductive Organ Female Reproductive Organ

STAMEN

Anther – Produces spermnuclei by meiosis.

Sperm nuclei are enclosed by pollen grains.

Filament - holds the anther up.

PISTIL

Stigma - Top of the pistil,sticky surface for pollen tostick.

Style - connects the stigma to the ovary.

Ovary – contains the ovules (eggs).

1. Pollination occurs when a pollen grain lands on a stigma.

2. A pollen tube grows down the style into the ovary and enters an ovule.

3. A sperm travels down the tube to fertilize one egg. This is called fertilization.

4. The resulting embryo then develops into

a seed.

Pollination/Fertilization

Pollen Sacs of theLily Anther

The pollen Tetrads in the Lily Anther formed by the meiotic division of the microspores in the pollen sacs. They will mature into fully formed pollen grains.

The Lily Ovulary Megaspore Mother Cell

It is a large diploid cell that undergoes meiosis to form four haploid megaspores.

The second meiotic division in the lily ovulary results in the formation of four haploid megaspore nuclei. They are not separated by cell walls in lilies.

WHAT IS A FRUIT?

1. Fruits come in all shapes and sizes.

2. It is the result of the thickening of the ovary wall which functions to protect the seeds inside and to aid in seed dispersal.

3. The tissue of a fruit may be fleshy and contain stored sugars and starches, i.e., apples and pears (the receptacle is the edible part).

4. They may be dry and hard and remained attached or fused to the ovary wall, i.e., walnuts and hazelnuts.

5. Many “vegetables” such as squash, eggplant and cucumbers are really fruits.

SIMPLEFRUITS:

Developed from asingle matured ovary in a singleflower.

AGGREGATEFRUITS:

Consists of a numberof matured ovaries formedin a single flower and arrangedover the surface of a singlereceptacle. Individual ovaries are called fruitlets.

MULTIPLE FRUITS:

Consists of the maturedovaries of many flowersmore or less united into asingle mass. Most are alsoaccessory fruits which meansthey have some other flowerpart united with the ovary.

THREE MAJORTYPES

of FRUITS

1. Two classes of angiosperms: monocots and dicots . Monocots have one cotyledon and dicots have two.

2. Cotyledons (seed leaves) are the first leaves produced by plants.

3. They are found in the seed or plant embryo.

4. They provide stored food and nutrients for the growing plant until the true leaves can grow and begin the process of photosynthesis.

5. Monocots and dicots have physical characteristics by which they can be identified: number of floral parts, by the array of their leaf veins, by their number of pores or furrows on the pollen grain and by the distribution of their vascular bundles.