Inflorescence – Class 11 | Chapter – 5 | Short Notes Series PDF

Inflorescence is the arrangement of flowers on the floral axis. The flowers are arranged with respect to a fixed floral axis. Depending on whether the apex gets converted into a flower or continues to grow, two major types of inflorescences are defined –

1. Racemose inflorescence– the main axis continues to grow, the flowers are borne laterally in an acropetal succession. Categories in the Racemose Inflorescence

  • Raceme: In this category, the flower is developed between the stem and the branch at the upper angle on an unbranched axis.
  • Spike: It is similar to raceme, but here the flower develops from the stem instead of being borne on pedicels.
  • Catkin: It is a spike where the flowers can be staminate(male) or carpellate(female)
  • Spadix: It is a spike borne on a flesh stem which is one of the members of the Araceae family. It contains thick, long as well fleshy pedicels while the flowers are small, sessile, and unisexual.
  • Corymb: Contains longer pedicels on the lower flowers as compared to the pedicels at the upper flowers. 
  • Umbel: Each pedicel in the umbel starts from the same point at the peduncle and forms a shape just like an umbrella.
  • Capitulum: The peduncle does not grow in the capitulum, instead it flattens and becomes broad or concave.

2. Cymose inflorescence – the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal order. Categories in the Cymose Inflorescence:

  • Uniparous or Monochasial: A sideway branch is produced at A time in Uniparous Cyme. The two types of uniparous are Helicoid cyme and Scorpioid cyme. 
  • Biparous: In Biparous, two sideway branches arise from the basal part of the peduncle. Some of the examples of biparous cyme are jasmine, teak, and mirabilis.
  • Multiparous: Numerous lateral branches are produced from the base of the flower and later end in a flower. 

Special Types of Inflorescence 

  • Cyathium: Cythium has a cup-shaped structure at the edge. The center of the cup-shaped structure contains female flowers, surrounded by small male flowers. This type of inflorescence can be found in Euphorbia, Pedilanthus, and Poinsettia. 
  • Verticillaster: Verticillaster is usually found in Lamiaceae. The leaves are arranged opposite of the stem in Lamiaceae. Examples of Verticillaster: Coleus, Salvia, and Ocimum.
  • Hypanthium: The peduncle is altered in a narrow cup-like structure in Hypanthium type of inflorescence.

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By Team Learning Mantras