WordNet records no synonym and no antonym for poppy mallow. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a plant of the genus Callirhoe having palmately cleft leaves and white to red or purple flowers borne throughout the summer
Synonyms, antonyms and the broader and narrower relations for poppy mallow come from Princeton University’s WordNet. Full sources and licences.