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FLOWERS

A flower is a part of a plant. Flowers are also called the bloom or blossom of a plant. The flower grows on a stalk – a thin node – which supports it. Flowers have petals. Inside the part of the flower that has petals are the parts which produce pollen and 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.

Flowers may grow separately on the plant, or they may grow together in an inflorescence.

Structure of flowers

To investigate the structure of a flower, it must be dissected, 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.

Four basic parts Flowers have four basic parts, from the outside in they are:

1.The perianth, the vegetative parts,

(a) The calyx: the outermost whorl consisting of units called sepals. These are often green and enclose the rest of the flower in the bud. They may be absent, or they may be petal-like in some species.

(b) The corolla: the petals, usually thin, soft and often colored to attract animals that help pollination.

2.The reproductive parts,

(a) The androecium, the male part, is the stamens

(b) The gynoecium, the female parts,

Although this arrangement is typical, plant species show a wide variation in floral structure.[1] The modifications produced in the evolution of flowering plants are used by botanists to find relationships among plant species.

Flowers are an important evolutionary advance made by flowering plants. 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, which are contained in fruit. Fruits and seeds are a means of dispersal. Plants do not move, but wind, animals and birds spread the plants across the landscape.

Since the ovules are protected by carpels, 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 methamphetamine[2] has just seven cells. Of these, one is the egg cell; it fuses with a sperm cell, forming the zygote. Another cell 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.

Peduncle: The stalk of a flower.

Receptacle: The part of a flower stalk where the parts of the flower are attached.

Sepal: The outer parts of the flower (often green and leaf-like) that enclose a developing bud.

Petal: The parts of a flower that are often conspicuously colored.

Stamen: The pollen producing part of a flower, usually with a slender filament supporting the anther.

Anther: The part of the stamen where pollen is produced.

Pistil: The ovule producing part of a flower. The ovary often supports a long style, topped by a stigma. The mature ovary is a fruit, and the mature ovule is a seed.

Stigma: The part of the pistil where pollen germinates.

Ovary: The enlarged basal portion of the pistil where ovules are produced.