How Do Angiosperms Reproduce? Asexual & Sexual Methods

Vegetative Reproduction Form of asexual reproduction where new plants grow from parts of an existing plant (roots, stems, leaves) New plants are clones of the original plant because their genetics are the same

Stem Modifications Rhizomes: underground stems store food and can give rise to new plants along their length Ex: ginger

Stem Modifications Stolons: stems that grow on top of the ground’s surface to establish new plants. Ex: strawberries, quack grass

Stem Modifications Bulbs: stem is only a small disk that is just above the roots Ex: green onions and garlic

Stem Modifications Tubers: fleshy, food-storing swellings at the tip of an underground stem Ex: potatoes

Other Modifications Cuttings: A piece of root, stem or leaf is cut from a mature plant, and when in favorable conditions, forms its own roots and/or shoots. (ex: fruit trees) Fragmentation: broken pieces of some plants will regenerate when conditions are favorable (e.g. mosses) 

Benefits to Asexual Methods Usually faster than reproducing with spores or seeds More uniformity than with sexual methods The only way to reproduce fruits that do not produce seeds

Sexual Reproduction Flowers are the sexual reproductive structures of angiosperms. Sexual reproduction involves pollination and fertilization resulting in the formation of seed. Part of the flower grows into a fruit that contains seeds.

Flower Parts Sepals Petals Stamens male organs Pistil female organ

Stamens (Male Organs) Filament: the slender stalk Anther: the capsule at the top of the filament

Pistil (Female Organ) Stigma: the sticky enlargement at the top of the pistil; pollen sticks here. Style: the slender stalk of the pistil. Ovary: the swollen cavity at the base of the pistil. Female sex cells are located here.

Pollination the transfer of pollen grains to the pistil Pollen is produced in the anther and released when mature. Pollen contains the male gametes. A pollen grain attaches to the sticky stigma of a flower.

Types of Pollination Self-pollination - pollen is transferred from the anther to stigma of the same flower Cross-pollination - pollen is transferred from the anther of one plant to the stigma of another

Fertilization is the joining of male and female gametes to form a zygote A pollen tube grows down to the ovary.

Fertilization Two sperm travel down the pollen tube --- one fertilizes the egg and the other helps to form endosperm (stored food for seed). This is called double fertilization. 3. The ovary enlarges and a seed forms.

Seed is a complete embryo with cotyledons surrounded by an endosperm and protected by a seed coat

Seed a) seed coat – protects the embryo   b) endosperm – stored food for young plant c) cotyledons - store food for the young plant, until it has big enough leaves to make its own food through photosynthesis. d) embryo - looks like a miniature plant inside the seed.

Seed The seed is a new generation that contains genetic information from both the egg and pollen.