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Merosity is the number of component parts in each whorl of a plant structure. It is most commonly used in the context of flowers, in which case it refers to the number of sepals in the calyx, the number of petals in the corolla, and the number of stamens in each whorl of the androecium. The term may also be used to refer to the number of leaves in leaf whorls.

Types of merosity include:

  • 2: dimery, dimerous, 2-merous
  • 3: trimery, trimerous, 3-merous
  • 4: tetramery, tetramerous, 4-merous
  • 5: pentamery, pentamerous, 5-merous
  • high number: polymery, polymerous, n-merous

See alsoEdit

Trimerous flower of Tulipa clusiana (the three sepals resemble petals)
Tetramerous flower of Correa alba
Pentamerous flower of Crassula ovata

Further readingEdit

  • Decraene, L. P. Ronse; Smets, E. F. (1994). "Merosity in flowers: Definition, origin, and taxonomic significance". Plant Systematics and Evolution. 191 (1–2): 83–104. doi:10.1007/BF00985344.