Merosity (from the greek "méros," which means "having parts") refers to the number of component parts in a distinct
whorl of a plant structure.
The term is most commonly used in the context of a
flower where it refers to the number of
sepals in a whorl of the calyx, the number of
petal
Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...
s in a whorl of the corolla, the number of
stamen
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filame ...
s in a whorl of the
androecium, or the number of carpels in a whorl of the
gynoecium. The term may also be used to refer to the number of leaves in a
leaf whorl.
The adjective ''n''-merous refers to a whorl of ''n'' parts, where ''n'' is any integer greater than one.
In nature, five or three parts per whorl have the highest frequency of occurrence, but four or two parts per whorl are not uncommon. Be aware that two consecutive whorls of dimerous petals are often mistaken for tetramerous petals.
If all of the whorls in a given floral arrangement have the same merosity, the flower is said to be isomerous, otherwise the flower is anisomerous.
For example, ''
Trillium'' is isomerous since all whorls are trimerous (one whorl of three sepals, zero or one whorl of three petals, two whorls of three stamens each, and one whorl of three carpels). ''Trillium'' also has one whorl of three leaves.
Gallery
See also
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Cyclic flower
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Floral diagram
Floral diagram is a graphic representation of flower structure. It shows the number of floral organs, their arrangement and fusion. Different parts of the flower are represented by their respective symbols. Floral diagrams are useful for flower ...
*
Floral formula
References
{{Reflist, refs=
[{{cite journal , last1=Ronse Decraene , first1=L. P. , last2=Smets , first2=E. F. , year=1994 , title=Merosity in flowers: definition, origin, and taxonomic significance , journal=Plant Systematics and Evolution , volume=191 , issue=1–2 , pages=83–104 , doi=10.1007/BF00985344 , url=https://www.academia.edu/25486804/Merosity_in_flowers_Definition_origin_and_taxonomic_significance , access-date=22 November 2019]
[{{cite web , last1=Eckel , first1=P. M. , title=A Grammatical Dictionary of Botanical Latin , url=http://www.mobot.org/mobot/latindict/keyDetail.aspx?keyWord=merus , access-date=22 November 2019]
Plant morphology