What is a flower?
• A flower isn´t an ornament or a present for someone, is the reproductive organ of plants.
The function of a flower is to produce seeds for the plant reproduction. For the plants, these seeds are the near generation.
The flower is a structure made up of modified leaves. It contains the reproductive organs of the plant where gametes are produced.
anther filament stamen P I S T I L
stigma
style ovary
corolla
calyx
sepal
petal
• Pollination: is the transfer of pollen from the anthers of a flower to the stigma of the same flower or of another flower.
• Consists of the union of a male gamete with the female gamete.
• Once a pollen grain reaches the stigma of a flower, it starts to develop a tube (pollen tube), which grows along the style until it reaches the ovary. • The male gametes travel through the pollen tube to reach the ovary, where the female gamete is.
• Male and female gametes join, fertilization takes place and the zygote is formed.
seed
The develop of the zygote
.
The fruit is formed around the seed in angiosperms: after fertilization , the flower loses the sepals, petals, stamens, style and stigma. The walls of the ovary get “fatter” and form the fruit with the seed inside. The fruit´s function is to protect the seed and help in its dispersion.
• The seed can be dispersed by: Wind Animals …… With this, the plant colonized places.
• If the conditions are good, when the seed fall to the ground will germinate. • 1º: seed absorbs the water so the coast breaks. • 2º: seed opens and the embbryo begins to develop creating a new plant. • At first, the new plant feeds on the supplies stored in the seed until it can carry out photosynthesis and begans to make its own nutrients.
anther filament corolla P I S T I L
stigma
style ovary
stamen
calyx
sepal
petal
Bibliography: • http://www.pollinatorparadise.com/what_is_ pollination.htm • Libro Natural Science bruño 1º ESO • Libro de Natural Science 2ºESO • Book of natural Science Anaya 1º ESO • Unit 6 Natural Science 1º ESO