Class 11 Biology
The arrangement of flowers on floral axis is called inflorescence. There are two major types of inflorescence, viz. racemose and cymose.
Racemose Inflorescence: In this type of inflorescence the main axis continues to grow. So, this is also called indeterminate inflorescence.Flowers are borne laterally in acropetal succession. In case of acropetal succession, the older flowers are at base and the younger flowers are at top.
Cymose inflorescence: In this type of inflorescence, the main axis terminates in a flower. Hence, the growth is limited in cymose inflorescence. So, this is also called determinate inflorescence. Flowers are borne in basipetal order; in this case, which means that the older flowers are at top and younger flowers are at the base.
The flower is a reproductive part of an agiospermic plant. The flower serves the purpose of sexual reproduction. In a typical flower, there are four kinds of whorls. These whorls are successively arranged on the swollen end of the stalk or pedicel. The swollen end of the stalk is called thalamus or receptacle.
Let us try to understand, how does a flower develop. The shoot apical meristem changes into flower meristem. After this, the internode becomes condensed, i.e. it no longer grows longitudinally. Then, different floral parts grow on this laterally.
Both androecium and gynoecium are present in a bisexual flower, but either of them is present in a unisexual flower.
Floral parts may be present in multiples of 3, 4 or 5 in a flower. Depending on this, a flower can be trimerous, tetramerous or pentamerous.
Bracteate Flower: The reduced leaf at the base of a flower is called a bract. A flower with bract is called bracteate flower.
Ebracteate Flower: A flower without a bract is called an ebracteate flower.
Tepals: In monocot plants, it is impossible to differentiate between sepals and petals because both look similar. In such a condition, these structures are called tepals.
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