• Written By Sankavi_E
  • Last Modified 24-05-2023

What is Inflorescence? 

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The inflorescence is the mode of development and arrangement of flowers on a stem or lateral branches. Inflorescences are complex structures which facilitate reproduction by presenting flowers in space and time, they also facilitate fruit development and seed dispersal. Inflorescence in reward-producing plants can facilitate pollination by attracting pollinators. Morphologically inflorescence is the modified part of the stem of seed plants where flowers are arranged on the stem or branches of a plant

In inflorescence, the pattern of flower development and the branching pattern of the axis (stem of inflorescence) has played an essential role in taxonomic studies. The enormous diversity of inflorescence is primarily due to natural selection. 

There are mainly two types of inflorescence based on the arrangement of flowers; if the flowers are arranged in an acropetal manner, the inflorescence is of racemose type. If the flowers are arranged in a basipetal manner, they are of cymose type. Based on the morphology and branching pattern, it is further classified into many types. Any flower in an inflorescence is termed floret only when the individual flowers are small and arranged in a tight cluster. The stem which holds the whole inflorescence is called a peduncle. 

What Are The Types Of Inflorescence?

When flowers are arranged in acropetal succession, i.e. the youngest flower at the apex and the older flower towards the base, the growth of the main axis is not terminated. This axis (stem) continuously produces flowers laterally. Such a category of the inflorescence is called racemose, this type is further classified based on the nature of the main axis and branching patterns.

  1. When the main axis is elongated: 

Raceme: Peduncle bears many pedicellate flowers in acropetal succession. 

Panicle: The peduncle is branched, and lateral branches show flowers arranged in a raceme manner. 

Corymbose: Similar to raceme, but the older flowers have elongated pedicels. Hence all the flowers in this inflorescence reach the same level. 

Spike: Similar to raceme but with sessile flowers. 

Catkin: Peduncle is unbranched and drooping. 

  1. When the main axis is shortened or compressed: 

Umbel: The main axis is highly reduced. Hence the pedicellate flowers appear to arise from a common point. 

Capitulum: Small sessile flowers aggregated densely on a condensed and flattened peduncle. 

When the flowers are arranged in basipetal succession, i.e., the oldest flower at the apex and younger flowers towards the base, in such case, growth of the main axis is checked by the formation of a flower, such a category of the inflorescence is called cymose. Based on the branching pattern, they are of the following types. 

  1. Monochasial Cyme: A single terminal flower arises from the peduncle, and a single lateral branch from the peduncle also bears a single terminal flower.
  2. Dichasial Cyme: Peduncle bears a single terminal flower and gives rise to two lateral branches, each bearing a single flower.
  3. Polychasial Cyme: Peduncle bears a single terminal flower and gives rise to more than two lateral branches, each with a single terminal flower.

What Is Cymose Inflorescence?

The cymose inflorescence is characterised by the presence of a flower at the apical part of the peduncle or inflorescence axis. The growth of the peduncle is terminated by the development of flowers in the apical tip. Flowers are arranged in basipetal succession, i.e. older flowers are at the apex, and younger flowers are at the base of the peduncle. In this flower arrangement, younger flowers are at the periphery, and older flowers are at the centre, i.e. near the peduncle. In this type of inflorescence, immature flower buds are present at the bottom of the peduncle, and the older flower buds are towards the apex of the peduncle. 

This type of inflorescence can be found in the Solanaceae family in plants such as Drosera, Begonia, Ranunculus, Jasmine, Calotropis, etc. Based on the branching pattern of the peduncle, they are classified into various types. In some plants, the cymose inflorescence is unusually modified to particular types, such as cyathium inflorescence found in members of the Euphorbia genus, Hypanthodium inflorescence present in members of the Ficus genus and Verticillaster inflorescence present in members of the Labiatae family. 

Polychasial Cyme

  1. Based on the branching pattern, the monochasial cymose inflorescence is further classified into two types: 
  • Scorpioid: In this type of inflorescence, lateral branches terminate in a single flower; these lateral branches arise from both sides of the peduncle. Ex: Sundew, Cotton, Heliotropium. 
  • Helicoid: In this type of inflorescence, lateral branches terminate in a single flower; these lateral branches always arise on the same side, forming a helical structure. Eg: Hamelia, Drosera, Myosotis. 
  1. Dichasial Cymose: Also known as biparous cyme, in this type of inflorescence, the peduncle terminates in flower and gives rise to two lateral branches; these lateral branches also terminate in flower. Eg: Saponaria, Jasmine, Ixora. 
  2. Polychasial Cymose: Also known as multiparous cyme, in this type of inflorescence, the peduncle bears a single terminal flower and gives rise to more than two lateral branches, each lateral branch with a single terminal flower. Ex: Calotropis. 

What Is the Difference Between Racemose And Cymose Inflorescence?

Students can find the differences between Cymose and Racemose inflorescence from the table below.

S. No.CymoseRacemose
1Peduncle terminates in flower. Peduncle does not terminate in flower.
2The growth of the peduncle is definite. The growth of the peduncle is indeterminate. 
3Sympodial or multipodial growth of peduncle.Monopodial growth of peduncle. 
4Flowers are arranged in basipetal succession or centrifugal arrangement. Flowers are arranged in acropetal succession or centripetal arrangement. 
5The first flower arises from the tip of the peduncle. The first flower arises from the base of the peduncle.
6A definite number of flowersIndefinite number of flowers.
7Flowers in the inflorescence blossom at long intervals.Flowers in the inflorescence blossom at short intervals.
8Flowers protect the newly formed fruits.Flowers do not protect the newly formed fruits.

Examples of Cymose Inflorescence

In plants such as sundew, cotton, and Heliotropium, the inflorescence is of monochasial cymose type, specifically called scorpioid cyme. In this type of monochasial cymose, lateral branches terminate in a single flower; these lateral branches arise from both sides of the peduncle. 

In plants such as Hamelia, Drosera, and Myosotis, the inflorescence is of monochasial cymose type and is specifically called helicoid cyme. In this type of monochasial cymose, lateral branches terminate in a single flower; these lateral branches always arise on the same side, forming a helical structure. This type of cymose arrangement is also seen in the male flowers of cyathium inflorescence. 

In plants such as Saponaria, Jasmine, and Ixora, the inflorescence is of dichasial cymose type. In this type of inflorescence, the peduncle terminates in the flower and gives rise to two lateral branches that terminate in the flower. In members of the Labiatae family, the inflorescence is of a particular type because the initial arrangement of flowers is of dichasial type, but further development of flowers is of monochasial scorpioid type. 

In plants such as Calotropis, the peduncle bears a single terminal flower and gives rise to more than two lateral branches, each with a single terminal flower. 

Cymose Inflorescence Experiment

Experiment Title – Cymose Inflorescence

Experiment Description – Have you ever seen tiny flowers coming together to form a single, larger cluster? This concept is called Inflorescence! In this virtual lab, learn about Cymose inflorescence. 

Aim of Experiment – To study and identify different types of cymose inflorescences

Material Required – Inflorescences of locally available plants like- Hibiscus, Hamelia, Heliotropium, Jasmine, Dianthus, and Calotropis.

Procedure –

  • Collect inflorescences of locally available plants and keep them in a water beaker. 
  • Make yourself familiar with the types and characters of inflorescences.
  • Identify the type of cyme inflorescences and tabulate them. 
  • Also, note the position of the inflorescence in the plant, i.e. axillary or terminal. 
  • Identify the arrangement of the oldest and youngest flowers on the peduncle. 
  • Also, note the position of the ovary with respect to the arrangement of other floral parts of the flower, namely epigynous, perigynous, and hypogynous.

Precautions – 

Students should read the precautions carefully before conducting the experiment.

  • Use fresh flowers and keep them in water to prolong their freshness.

FAQs on Cymose Inflorescence Experiment

Students can check the FAQs related to the cymose inflorescence experiment below.

Q1: Define inflorescence.
Ans: The inflorescence is the mode of development and arrangement of flowers on a stem or lateral branches. 

Q2: Define cymose inflorescence.
Ans: The cymose inflorescence is characterised by the presence of a flower at the apical part of the peduncle or inflorescence axis. Flowers are arranged in basipetal succession, i.e. older flowers are at the apex, and younger flowers are at the base of the peduncle. 

Q3: What are the advantages of flowers in inflorescence?
Ans: Inflorescences are complex structures which facilitate reproduction by presenting flowers in space and time, they also facilitate fruit development and seed dispersal. Inflorescence in reward-producing plants can facilitate pollination by attracting pollinators. 

Q4: Mention the characteristics of peduncle in cymose inflorescence
Ans: The growth of the peduncle is terminated by the development of flowers in the apical tip. Immature flower buds are present at the bottom of the peduncle, and the older flower buds are towards the apex of the peduncle. 

Q5: List the types of cymose of inflorescences.
Ans: The types of cymose inflorescences are as follows:

  1. Monochasial cymose is further classified into Helicoid cyme and Scorpioid cyme.
  2. Dichasial cymose
  3. Polychasial cymose
  4. Cyathium, verticillaster, and hypanthium are also modified types of cymose inflorescences.

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