The pattern of flower arrangement on the floral axis is known as inflorescence. Inflorescence is divided into two main types:
- Racemose: In racemose types of inflorescence, the main axis grows continuously and flowers are present laterally on the floral axis. Flowers are present in an acropetal manner
- Cymose: In the cymose type of inflorescence, the main axis does not grow continuously. A flower is present terminally on the main axis. The flowers are borne in a basipetal order. The main axis has limited growth
Other than these two, there are three special types of inflorescence present.
- Hypanthodium: The main axis forms a cup-shaped structure with a cavity having both male and female flowers and a small apical opening. E.g. Ficus
- Cyathium: Here the cup-shaped structure is formed from involucre of bracts. The single female flower is present in the middle, which is surrounded by numerous stalked male flowers. E.g. Euphorbia
- Verticillaster: This type of inflorescence is typical of plants with opposite leaves. It has two clusters of sessile flowers developing from the two opposite axils of leaves. Each cluster has a dichasial cyme arrangement. E.g. Ocimum, Salvia
Difference between Cymose and Racemose inflorescence
|1.||The main axis terminates in a flower and has definite growth||The main axis continues to grow indefinitely|
|2.||Peduncle shows sympodial or multipodial growth||Peduncle shows a monopodial growth|
|3.||The flower is present apically in basipetal succession||The flowers are present laterally in acropetal succession|
|4.||The arrangement of flowers is centrifugal||The arrangement of flowers is centripetal|
|5.||The grouping of flowers is more common||The grouping of flowers is less common|
|6.||The first formed flower is at the tip of peduncle||The first formed flower is at the base of the peduncle|
|7.||The number of flowers is definite||The formation of flowers is indefinite or unrestricted|
|8.||Flowers bloom at a long interval||Flowers bloom at a short interval|
|9.||Newly formed fruits are protected by flowers||Newly formed fruits are not protected by flowers|
“The cymose inflorescence is characterised by the presence of a flower at the apex of the flower axis.”
The growth of the main axis is limited and the lateral axis also terminates into flower and that limits the growth of the axis. Flowers are present in the basipetal succession, i.e. older flower is present terminally and the younger ones at the base. This type of arrangement is known as centrifugal with the older flowers present in the middle and the younger ones at the periphery.
Types of Cymose Inflorescence
There are four main types of cymose inflorescence:
- Monochasial cyme
- Dichasial cyme
- Polychasial cyme
- Cymose capitulum
- Monochasial cyme: It is also known as uniparous cyme. The main axis terminates in flower and it produces one lateral branch from the base, which also terminates in a flower. Each lateral and subsequent branch also produces one lateral branch with a terminal flower. Monochasial cyme is further divided into two types:
- Scorpioid: Lateral branches develop alternately on both sides of the axis e.g. Gossypium, Sundew
- Helicoid: Lateral branches develop on the same side forming a helix e.g. Begonia, Heliotropium
- Dichasial cyme: It is known as biparous cyme. The terminal peduncle terminates in flower. It gives rise to two lateral branches with terminal flower. Subsequent branches also behave similarly. E.g. Jasmine, Teak Saponaria
- Polychasial cyme: It is known as multiparous cyme. Multiple branches arise at the base of the apical flower on the peduncle. The oldest flower is in the middle. E.g Calotropis
- Cymose capitulum: In this type of arrangement the peduncle is reduced to a circular disc. The older flowers develop at the centre of the disc and the younger flowers at the periphery. This is known as centrifugal arrangement. E.g. Acacia, Mimosa
Frequently Asked Questions
What is Cymose type of inflorescence?
The cymose type of inflorescence is characterised by the presence of flower terminally on the main axis. Therefore the main axis has limited growth.
What is Racemose and Cymose?
Racemose and cymose are two types of inflorescence, i.e. arrangement of flowers around the main axis. In racemose, the main axis continues to grow indefinitely and the flowers are borne laterally. In cymose inflorescence, flowers are borne terminally on the floral axis and shows determinate growth of the main axis.
What is the main difference between Racemose and Cymose inflorescence?
The main difference between racemose and cymose inflorescence is that the flowers are borne laterally and the main floral axis continues to grow in the racemose inflorescence, whereas in the cymose type, flowers are borne terminally on the floral axis and the main axis shows limited growth. Flowers are borne in an acropetal manner (new flowers present at top) in racemose type, whereas in cymose type, flowers are borne in basipetal fashion (new flowers present at the bottom).
Which plant shows Cymose inflorescence?
Some examples of plants with cymose inflorescence are Solanum nigrum, Drosera, Begonia, Ranunculus, Jasmine, Calotropis, etc.
What is Polychasial cyme?
It is also known as multiparous cyme. Multiple branches arise at the base of the apical flower on the main floral axis. The lateral branches often become dichasial and then monochasial. The oldest flower lies in the middle. E.g Calotropis
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