Product Code Database
| dimerous, 2-merous |
| trimerous, 3-merous |
| tetramerous, 4-merous |
| pentamerous, 5-merous |
| polymerous |
| oligomerous |
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. 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.
| isomerous |
| anisomerous |
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