Inflorescence: Flower Arrangement on a Stem

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of the main branch or a complicated arrangement of branches. Inflorescence can also be defined as the reproductive portion of a plant that bears a cluster of flowers in a specific pattern.

Inflorescences are described by many different characteristics including how the flowers are arranged on the peduncle, the blooming order of the flowers and how different clusters of flowers are grouped within it. These terms are general representations as plants in nature can have a combination of types.

Types of Inflorescence

  • Catkin – A spike with only pistillate or staminate flowers (alder, poplar, walnut, and willows)
  • Composite or Head – A daisy-type flower composed of ray flowers (usually sterile with attractive, colored petals) around the edge and disc flowers that develop into a seed in the center of the flathead (sunflower and aster) On some composites, the ray and disc flowers are similar (chrysanthemums and dahlias)
  • Corymb – Stemlets (pedicels) arranged along the main stem. Outer florets have longer pedicles than inner florets giving the display a flat top. (yarrow, crabapple)
  • Cyme – A determinate, flat or convex flower, with inner floret opening first.
Types of Inflorescence
Types of Inflorescence
  • Panicle – An indeterminate flower with repeated branching. It can be made up of racemes, spikes, corymbs, or umbels. (Begonia)
  • Raceme – A modification of a spike with flowers attached to the main stem (peduncle) by stemlets (pedicel). (snapdragon, bleeding heart, Canterbury bells)
  • Solitary (or single) – One flower per stem (tulip, crocus)
  • Spadix – Showy part is a bract or spathe, partially surrounding the male and female flowers inside. (calla, caladium)
  • Spike – Flowers attached to the main stem, without stemlets, bottom florets open first. (gladiolus, ajuga, and gayfeather)
  • Umbel – Florets with stemlets attached to the main stem at one central point, forming a flat or rounded top. Outer florets open first. (dill, onion)
  • Symmetrical – Symmetrical flowers (lily)
  • Asymmetrical – Asymmetrical flowers (snapdragon)



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