Study and identification of different types of inflorescence (cymose and racemose)

Aim Of The Experiment

To study and identify different types of Inflorescences(racemose/cyme).

Theory

In angiosperms, the flowers are either borne singly or clusters. Flowers that are borne individually are by themselves, solitary whereas the flowers that are produced in a group or a cluster on a shared stalk or peduncle go on to form an inflorescence.

What is inflorescence?

In a flowering plant, the inflorescence is a cluster of flowers seen on a branch or branches. On the basis of flower arrangement on the peduncle(main axis) and flower timing (indeterminate and determinate), inflorescence can be classified into the following:

Racemose type

    • Simple raceme – The pedicellate bisexual flowers are arranged in an acropetal succession on an elongated peduncle. Example – Crotalaria
    • Spike – Similar to simple raceme except that the flowers are sessile.Example – Achyranthes
    • Compound Spadix – Unisexual male and female flowers sessile flowers are arranged in acropetal succession. Example – Cocos nucifera
    • Capitulum – Inflorescence axis is flattened to form a receptacle wherein ligulate ray florets and tubular disc florets develop in a centripetal manner. Example – Tridax

Cyme type

    • Solitary cyme – The Peduncle ends up in a flower. Example – Hibiscus
    • Helicoid cyme – Flowers are consecutively produced on one side on the peduncle to give a helicoid appearance. Example – Hamelia
    • Dichasial – The peduncle ends up with a flower and two lateral flowers are produced under the central flower one on each side for a cluster of three flowers to be formed. Example – Jasminum.
    • Polychasial cyme- Same pattern of development of flowers as seen in dichasial additionally it is continued here. Centrifugal mode of development. Example – Calotropis

Special Types

  • Cyathium – Inflorescence is protected by an involucre of five bracts wherein a nectary gland is connected to it. One female achlamydeous flower centrally with a long pedicel bringing the ovary out of the involucral cup. Male flowers are achlamydeous, found in 5 bundles corresponding to 5 bracts. Example: Euphorbia geniculata
  • Hypanthodium – Inflorescence is pear-shaped with an opening at the tip known as Ostiole causing a cavity inside. Example: Ficus

Materials Required

  • Inflorescence of any plant locally available
  • Hand lens
  • Water
  • Beaker

Procedure Of The Experiment

  • Pick some inflorescences of locally available plants
  • Place them in a beaker
  • Make yourself familiar with the types and characteristics of different inflorescences
  • Sort the inflorescences into cymose and racemose
  • List the different plant species in a table
  • Identify the different types of inflorescence with justification
  • Make a note of the location of the inflorescence in the plant which can either be terminal or axillary.
  • Sketch out labelled diagrams of the inflorescence of each of the samples collected for the experiment indicating the arrangement of the youngest and the oldest flowers on the main axis
  • Sketch a diagram of a flower of every inflorescence. Label different parts after identification.
  • Position of the ovary is noted corresponding to the floral parts arranged i.e., perigynous, epigynous, hypogynous.

Inference

  • Inflorescence can either be of the type-indefinite or definite. Classification is based on
  • Position on the mother axis i.e., terminal or axillary
  • Maturity of flowers
  • Number of flowers
  • Inflorescence and characteristics of flowers assist in plant parts identification and taxonomic classification
  • Observe the inflorescence type that is common in the locally available plants.

Explore more biological concepts and other experiments on imbibition, and transpiration by registering at BYJU’S.

Further Reading

Flowers And Inflorescence
Solanaceae, Fabaceae, Liliaceae: Family Description
Flowers – Parts of flower And Function
Test your knowledge on Study And Identification Of Different Types Of Inflorescence

Comments

Leave a Comment

Your Mobile number and Email id will not be published.

*

*