Merosity

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

• 

  Tulipa clusiana: trimerous

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  Correa alba: tetramerous

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  Crassula ovata: pentamerous

Further reading

• 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.