Topic 13 - Plant Reproduction

monoecious flower

• Both the male and female reproductive parts on the same plant on separate flowers

• This allows for both self and cross-pollination

• The male and female flowers are distinct and separate

• Example: Corn (the male tassels at the top and the female silks lower down)

dioecious flower

• The male and female reproductive organs are on separate individual plants

• The male and female reproductive organs should be in close proximity for pollination to occur

• Example: Zucchini flowers

gametophytes

haploid portion of life cycle

sporophyte

diploid portion of life cycle

self-pollination

transfer of pollen from the anther to the stigma of the same flower or another flower of the same plant

cross-pollination

transfer of pollen from the anther of one flower to the stigma of different plant of the same species

1. Pollination by wind

2. Pollination by insects

3. Pollination by Bats

4. Pollination by Birds

agents of pollination:

endosperm

One sperm fertilizes the egg, forming the zygote. The other sperm combines with the two polar nuclei of the embryo sac’s large central cell, forming a triploid cell that develops into the nutritive tissue called _____

endosperm development

• Diploid nucleus of the ovule’s central cell divides, forming a multinucleate “supercell” that has a milky consistency

• Stores nutrients that can be used by the seedling after germination

• Food reserves of the endosperm are completely exported to the cotyledons before the seed completes its development; consequently, the mature seed lacks endosperm

suspensor

The basal cell continues to divide, producing a thread of cells called the _____, which anchors the embryo to the parent plant and helps in transferring nutrients to the embryo from the endosperm.

fruit development

• Fertilization triggers hormonal changes that cause the ovary to begin its transformation into a fruit

• If a flower has not been pollinated, fruit typically does not develop, and the entire flower usually withers and falls away

• Ovary wall becomes the pericarp

pericarp

the thickened wall of the fruit

simple fruit

• develops from a single carpel (or several fused carpels) of one flower

• e.g. pea, lemon, peanut

aggregate fruit

• develops from many separate carpels of one flower

• e.g. raspberry, blackberry, strawberry

multiple fruit

• develops from many carpels of the many flowers that form an inflorescence

• e.g. pineapple, fig

accessory fruit

• develops largely from tissues other than the ovary

• in the apple fruit, the ovary is embedded in a fleshy receptacle

1. simple fruit

2. aggregate fruit

3. multiple fruit

4. accessory fruit

developmental origin of fruits (types of fruit):

1. berry

2. drupe

3. follicle

4. legume

5. capsule

6. caryopsis

7. achene

8. nut

9. aggregate fruit

10. multiple fruit

11. accessory fruit

fruit types:

berry

a simple, fleshy fruit in which the fruit wall is soft throughout (tomato)

drupe

a simple, fleshy fruit in which the inner wall of the fruit is a hard stone (peach)

follicle

a simple, dry fruit that splits open along one suture to release its seeds; fruit is formed from ovary that consists of a single carpel (milkweed)

legume

a simple, dry fruit that splits open along two sutures to release its seeds; fruit is formed from ovary that consists of a single carpel (green bean)

capsule

a simple, dry fruit that splits open along two or more sutures or pores to release its seeds; fruit is formed from ovary that consists of two or more carpels (iris)

caryopsis

a simple, dry fruit in which the fruit wall is fused to the seed coat (wheat)

achene

a simple, dry fruit in which the fruit wall is separate from the seed coat (sunflower)

nut

a simple, dry fruit that has a stony wall, is usually large, and does not split open at maturity (oak)

aggregate fruit

a fruit that develops from a single flower with several to many pistils (i.e., carpels are not fused into a single pistil) (blackberry)

multiple fruit

a fruit that develops from the ovaries of a group of flowers (mulberry)

accessory fruit

a fruit composed primarily of non-ovarian tissue (such as the receptable or floral tube) (apple)