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Having or designating floral whorls with equal numbers of parts in each whorl.


1. (Biology) having an equal number of parts or markings
2. (Botany) (of flowers) having floral whorls with the same number of parts. Compare anisomerous


(aɪˈsɒm ər əs)

1. having an equal number of parts, markings, etc.
2. (of a flower) having the same number of members in each whorl.
References in periodicals archive ?
Delimitation is commonly not problematic, because calyx and corolla both occur in an isomerous whorl or series of sepals and petals.
Androecium: stamens 4-5(-12), isomerous, alternipetalous, sometimes strongly zygomorphic and adnate to corolla tube or mouth, rarely some staminodal or even obsolete (Hoppea): anthers tetrasporangiate, usually introrse (extrorse in Gentiana) and dithecal; dehiscing via a longitudinal slit or rarely by terminal pores (Exacum); occasionally connate (Voyria); occasionally connective with one to two apical glands (Sebaea); rarely with long thread-like projections (Urogentias).
Minor monosymmetry is also present in flowers in which the floral whorls are not isomerous (or asymmetric if the symmetry plane is oblique).