Flower
A flower is a part of a plant. Flowers are also called the bloom or blossom of a plant. It sometimes has a stem – a thin pipe – to support the flower. Flowers have petals. The flower contains the part that produces seeds.
Flowers are the reproductive structure of flowering plants, which are plants of the division Magnoliophyta, also called the Angiosperms).
In many plants, a flower is its most colourful part. We say the plant 'flowers', 'is flowering' or 'is in flower' when this colourful part begins to grow bigger and open out. There are many different kinds of flowers in different areas in the world. Even in the coldest places, for example the Arctic, flowers can grow during a few months.
Structure of flowers
In botany, flowers are the key evolutionary advance made by flowering plants. To investigate the structure of a flower, it must be dissected, examined under a binocular microscope, and its structure summarised by a floral diagram or a floral formula. Then its family can be identified with the aid of a flora, which is a book designed to help you identify plants.
Flowers contain the reproductive organs of a plant. Some flowers are dependent upon the wind to move pollen between flowers of the same species. Many others rely on insects or birds to move pollen. The role of flowers is to produce seeds or fruit (fruits contain seeds). Fruits and seeds are a means of dispersal. Plants do not move, but wind, animals and birds spread the plants across the landscape.
Evolution of flowers
a: sporangia borne at tips of leaf
b: Leaf curls up to protect sporangia
c: leaf curls to form enclosed roll
d: grouping of three rolls into a syncarp
Flowers are modified leaves possessed only by the group known as the angiosperms, which are relatively late to appear in the fossil record.
The flowering plants have long been assumed to have evolved from within the gymnosperms; but gymnosperms form a clade which is distinct from the angiosperms. The two clades diverging some 300 million years ago.[1]
Since the ovules are protected by carpels and integuments, it takes something special for fertilisation to happen. Angiosperms have pollen grains comprising just three cells. One cell is responsible for drilling down through the integuments, and creating a passage for the two sperm cells to flow down. The megagametophyte[2] has just seven cells; of these, one fuses with a sperm cell, forming the nucleus of the egg itself, and another other joins with the other sperm, and dedicates itself to forming a nutrient-rich endosperm. The other cells take auxiliary roles. This process of "double fertilisation" is unique and common to all angiosperms.
Flowers and flowering plants first appear in the fossil record of 130 million years ago in the Lower Cretaceous.[3][4]
Flowers for people
As decoration
Flowers have long been admired and used by humans. Most people think that flowers are beautiful. Many people also love flowers for their fragrances (scents). People enjoy seeing flowers growing in gardens. People also enjoy growing flowers in their backyards, outside their homes. People often wear flowers on their clothes or give flowers as a gift during special occasions, holidays, or rituals, such as the birth of a new baby (or a Christening), at weddings (marriages), at funerals (when a person dies). People often buy flowers from businesses called florists.
As a name
Some parents name their children after a flower. A couple of common flower names are: Rose, Lily, Daisy and Jasmine.
As food
People also eat some types of flowers. Flower vegetables include broccoli, cauliflower and artichoke. The most expensive spice, saffron, comes from the crocus flower. Other flower spices are cloves and capers. Hops flowers are used to flavor beer. Dandelion flowers are often made into wine.
Honey is flower nectar that has been collected and processed by bees. Honey is often named for the type of flower that the bees are using (for example, clover honey). Some people put flowers from nasturtiums, chrysanthemums, or carnations in their food. Flowers can also be made into tea. Dried flowers such as chrysanthemum, rose, jasmine are used to make tea.
Special meanings
Flowers were used to signal meanings in the time when social meetings between men and women was difficult. Lilies make people think of life. Red roses make people think of love, beauty, and passion. In Britain, Australia and Canada,Poppies are worn on Memorial Day as a mark of respect for those who served and died in wars. Daisies make people think of children and innocence.
List Of Common Flowers
- Rose
- Lily
- Water Lily
- Sunflower
- Petunia
- Jasmine
- Tulip
- Hibiscus
- Dahlia
- Daffodil
- Uniflora
- Pansy
- Daisy
- Marigold
- Morning Glory
- Edelweiss
Other websites
Relevant pages
References
- ↑ Nam, J.; Depamphilis, CW; Ma, H; Nei, M (2003). "Antiquity and Evolution of the MADS-Box Gene Family Controlling Flower Development in Plants". Mol. Biol. Evol. 20 (9): 1435–1447. doi:10.1093/molbev/msg152. PMID 12777513.
- ↑ tiny haploid female plant which includes the egg.
- ↑ Crepet W.L. (2000). "Progress in understanding angiosperm history, success, and relationships: Darwin's abominably "perplexing phenomenon"". Proceedings of the National Academy of Sciences. 97 (24): 12939–41. doi:10.1073/pnas.97.24.12939. PMC 34068. PMID 11087846.
- ↑ Wilson Nichols Stewart & Gar W. Rothwell 1993Paleobotany and the evolution of plants. 2nd ed, Cambridge Univ. Press.