Sexual Reproduction Sexual Reproduction in Plantsin Plants

The SeedThe Seed

The seed is the product of sexual reproduction The seed is the product of sexual reproduction in most plants.in most plants.

The seed contains an embryo, a food supply The seed contains an embryo, a food supply and a seed coat that keeps it from drying out.and a seed coat that keeps it from drying out.

Seed-bearing plants can be classified into two Seed-bearing plants can be classified into two groups based on seed structure.groups based on seed structure.

The two groups are called The two groups are called AngiospermsAngiosperms and and Gymnosperms.Gymnosperms.

AngiospermsAngiosperms

Angiosperms are Angiosperms are flowering plantsflowering plants

The seeds form The seeds form inside the flowerinside the flower

When mature the When mature the seeds are enclosed seeds are enclosed in a case.in a case.

Sexual Reproduction in Sexual Reproduction in AngiospermsAngiosperms

The flowers produced by angiosperms The flowers produced by angiosperms contain the plant’s reproductive organscontain the plant’s reproductive organs

The female reproductive organs are The female reproductive organs are called the called the pistilpistil

The male reproductive organs are called The male reproductive organs are called the the stamenstamen

Pollination Pollination

In order for the seeds In order for the seeds to develop, pollen to develop, pollen grains from the grains from the anthers must reach anthers must reach the stigma of the the stigma of the pistil.pistil.

This process is This process is called pollinationcalled pollination

There are two types of pollination used There are two types of pollination used by angiosperms;by angiosperms; Self-pollinationSelf-pollination - the males and female - the males and female

gametes come from the same plantgametes come from the same plant Cross –pollinationCross –pollination – the male and female – the male and female

gametes come from two different plants. The gametes come from two different plants. The two most common agents of cross-two most common agents of cross-pollination are wind and insects.pollination are wind and insects.

FertilizationFertilization

The pollen grain must The pollen grain must grow a pollen tube to grow a pollen tube to reach the ovulereach the ovule

When the pollen When the pollen reaches the ovule a reaches the ovule a zygote and a zygote and a cotyledoncotyledon are are formed.formed.

The cotyledon The cotyledon contains stored food.contains stored food.

GymnospermsGymnosperms

Gymnosperms do Gymnosperms do not produce flowersnot produce flowers

Produce seeds Produce seeds inside the conesinside the cones

Seeds have a coat Seeds have a coat that protects them that protects them but are not inside a but are not inside a casecase

Sexual Reproduction in Sexual Reproduction in GymnospermsGymnosperms

Gymnosperms produce their seeds Gymnosperms produce their seeds inside cones. For this reason they are inside cones. For this reason they are called called conifersconifers..

In some species male and female cones In some species male and female cones are produced on separate trees.are produced on separate trees.

In most conifers male and female cones In most conifers male and female cones are produced by each tree.are produced by each tree.

Pollination and Pollination and FertilizationFertilization

Pollination proceeds Pollination proceeds the same as in the same as in angiospermsangiosperms

Fertilization also Fertilization also requires the requires the formation of a pollen formation of a pollen tube to allow the tube to allow the pollen to reach the pollen to reach the egg.egg.

Plants without seedsPlants without seeds

Plants such as Plants such as mosses and ferns mosses and ferns reproduce through reproduce through sporesspores

Like gametes Like gametes spores are haploid spores are haploid however, however, a spore a spore can develop into a can develop into a new plant without new plant without fertilization.fertilization.

The mature form called a sporophyte will The mature form called a sporophyte will release the sporesrelease the spores

Under the correct conditions the spore will Under the correct conditions the spore will develop into a gametophyte.develop into a gametophyte.

The two main advantages for dispersal are; The two main advantages for dispersal are; that they are light and that they can survive that they are light and that they can survive unfavourable conditions by staying dormant unfavourable conditions by staying dormant until the conditions are ideal.until the conditions are ideal.