A black flower with brilliant red and purple centers... Caralluna Russelliana
Look down to the stem.
Thick (up to 4 inches) light gray-green stems, mostly four or five angled, plants up to 24" tall with softball sized clusters of dark purple one inch flowers. Finally I am seeing it flower! Yes, a truly black flower ball about 6 inches around with pink and red centers!
Asclepiadeaceae: Herbs, shrubs, or rarely treelike, with milky or, less often, clear latex. Leaves simple, opposite or occasionally whorled, very rarely alternate, usually without obvious stipules, margin nearly always entire. Inflorescences terminal, axillary, or extra-axillary, cymose, often condensed and umbel-like, occasionally a racemelike bostrychium.
Fairchild Tropical Botanic Garden, Miami, FL