Plant Sexual Reproduction

Sexual Reproduction in Plants

• There are approximately 390,900 plant species known to science, and sexual reproduction is a key factor in this diversity.

Parts of a Flower

• Petals and sepals help protect the flower bud and can be brightly colored or scented to attract pollinators.
• The stem and receptacle connect the flower to the rest of the plant.
• The stamen is the male part of the flower, consisting of an anther where pollen is produced and the filament, which is the stalk that supports the anther.
• The carpel is the female part of the flower, consisting of the stigma, style, and ovary.
• The stigma is a sticky landing for pollen, the style is where the pollen grain descends, and the ovary is where the female gametes or ovules are located.

Pollination

• Pollination is the transfer of pollen from the male anther of one flower to the female stigma of another flower.
• Flowers can be pollinated in different ways, including by wind, water, or pollinators such as insects, birds, and other animals.
• Flowers pollinated by pollinators are structurally different from those pollinated by wind or water, with differences in size, scent, and color of petals, and positioning of stamen and style.

Fertilization

• Fertilization results in the production of seeds.
• A mature pollen grain containing two male cells lands on the female stigma of the same species, grows a pollen tube, and travels down to the ovary, where it enters through an opening called the micropile.
• One male cell fuses with the female egg, fertilizing it, and develops into the seed.
• The other male cell attaches to two cells in the embryo sac, forming an endosperm, which provides starchy food for the seed to grow.

Dispersal of Fruits and Seeds

• The ovary enlarges and becomes a fruit, surrounding the internal seeds.
• Fruits and seeds are dispersed in many ways, including by humans, where they will again grow into a new plant under the correct conditions.

Sexual Reproduction in Plants

• Approximately 390,900 plant species are known to science, and sexual reproduction is a key factor in this diversity.

Parts of a Flower

• Petals and sepals protect the flower bud and attract pollinators with bright colors and scents.
• The stem and receptacle connect the flower to the rest of the plant.
• The stamen consists of an anther, which produces pollen, and a filament that supports the anther.
• The carpel is the female part of the flower, comprising the stigma, style, and ovary.
• The stigma is a sticky surface for pollen, the style allows pollen grain descent, and the ovary contains female gametes or ovules.

Pollination

• Pollination involves the transfer of pollen from the male anther to the female stigma of another flower.
• Flowers can be pollinated by wind, water, or pollinators like insects, birds, and other animals.
• Flowers adapted for pollinators have distinct structures, including size, scent, and petal color, and positioning of stamen and style.

Fertilization

• Fertilization produces seeds.
• A mature pollen grain grows a pollen tube, traveling down the style to the ovary, where it enters through the micropile.
• One male cell fuses with the female egg, fertilizing it, and develops into a seed.
• The other male cell forms an endosperm, providing starchy food for seed growth.

Dispersal of Fruits and Seeds

• The ovary enlarges and becomes a fruit, surrounding internal seeds.
• Fruits and seeds are dispersed through various means, including human activity, leading to new plant growth under suitable conditions.