details about flower

Form and types
flower parts
flower parts
(Left) Generalized flower with parts; (right) diagram showing arrangement of floral parts in cross section at the flower's base
Basically, each flower consists of a floral axis upon which are borne the essential organs of reproduction (stamens and pistils) and usually accessory organs (sepals and petals); the latter may serve to both attract pollinating insects and protect the essential organs. The floral axis is a greatly modified stem; unlike vegetative stems, which bear leaves, it is usually contracted, so that the parts of the flower are crowded together on the stem tip, the receptacle. The flower parts are usually arrayed in whorls (or cycles) but may also be disposed spirally, especially if the axis is elongate. There are commonly four distinct whorls of flower parts: (1) an outer calyx consisting of sepals; within it lies (2) the corolla, consisting of petals; (3) the androecium, or group of stamens; and in the centre is (4) the gynoecium, consisting of the pistils.

pistil
pistil
The sepals and petals together make up the perianth, or floral envelope. The sepals are usually greenish and often resemble reduced leaves, while the petals are usually colourful and showy. Sepals and petals that are indistinguishable, as in lilies and tulips, are sometimes referred to as tepals. The androecium, or male parts of the flower, comprise the stamens, each of which consists of a supporting filament and an anther, in which pollen is produced. The gynoecium, or female parts of the flower, comprises one or more pistils, each of which consists of an ovary, with an upright extension, the style, on the top of which rests the stigma, the pollen-receptive surface. The ovary encloses the ovules, or potential seeds. A pistil may be simple, made up of a single carpel, or ovule-bearing modified leaf; or compound, formed from several carpels joined together.