Ageratums rhymes with:
argosystems, atoms, autumn's, bantam's, bantams, biosystems, bottom's, bottoms, cablesystems, customs, ecosystems, items, microsystems, microsystems', mortems, phantoms, quantum's, subsystems, symptoms, system's, systems, systems', techsystems, totems, ultimatums, ultrasystems, victim's, victims
Ageratums sounds like:
accordance, according, accordions, accreditations, accrediting, ascertaining, asserting, assertions, awkwardness